BATTLETECH has a lot of achievements, at 128. Luckily for we achievement hunters out there, most of them come from simply playing the game long enough, and only a couple require stupid amounts of luck and/or prior planning. This will be a quick, ugly run-down of best ways to knock out all 128.

As of 5.10.18, this guide is still a work-in-progress. Please don't comment "hey you forget [achievement]" - i'm working on all of them, and ideally it'll be done soon. Please feel free to comment alternate ways of ticking off achievements that are listed, as I'm very interested if someone else manages to figure out a better way of doing things.

Version History:
11.28.18: Whoops. I'm actually still alive, although this project definitely fell to the backburner after I burned out on Battletech. I'll be making an effort to finish the 1.0 achieves as well as the ones added in the Flashpoint update. Some of these may be theoretical strategies, as Valkyria Chronicles 4 is out and I don't really want to replay the entire Campaign again just because HBS added Ironman 7 months post-launch.
5.30.18: Still alive. I've added in a couple of achievements, mostly for the Campaign. More importantly, I've added what information I have about Complete Roster, which has been notoriously buggy.
5.10.18: v.67: 73/109 achievements listed, currently text-only. To-Do: Finish up all achievements, add images, clean up sort order to reflect how your achievements will look at 100%.

All of these are earned during the Restoration Campaign. Story achievements are unmissable.

A MechWarrior's Path - Established a history
Awarded after character creation.

Coromodir Lost - Suffered a terrible betrayal
Finish the Prologue.

Argo Rising - Recovered an ancient ship
Complete Axylus

Why We Fight - Started a war
Complete First Strike.

House Decimis Restored - Liberated the world of Panzyr
Complete Liberation: Panzyr.

House Karosas Restored - Liberated the world of Smithon
Complete Liberation: Smithon.

Family Reunion - Captured a villain
Complete Served Cold.

Grave Robber - Discovered ancient technology
Complete Raising the Dead.

House Gallas Restored - Liberated the world of Itrom
Complete Liberation: Itrom.

Necessity over Conscience - Learned an important secret
Complete Extraction.

House Parata Restored - Liberated the world of Tyrlon
Complete Liberation: Tyrlon.

The Sword of Restoration - Invaded a capital
Complete Locura (Coromodir Pt. 1).

A Hero Forged - Crowned a rightful ruler
Complete Showdown (Coromodir Pt. 2) and the Restoration Campaign.

I Am Iron Man! - Completed a Campaign with Iron Man enabled
Since Ironman wasn't available until 1.3, this will require a new campaign if you've already completed the game. The game doesn't seem to be picky about other difficulty settings, so feel free to up payouts and salvage and lower enemy force strength. Otherwise, take it slow and build up your forces so that you can overpower encounters since there's no going back on a decision.

Professional Scavenger - Start a campaign with 'Mechs requiring 8 parts, then complete 10 'Mechs
You'll need to start a new campaign with custom difficulty options, then set it so that Mechs require 8 partial mech salvage to rebuild. I recommend you also switch salvage rights and contract pay to generous while you're there so that this is less of a slog. Keep in mind as you play that maximum salvage comes from headshots or pilot kills, then legging a mech, and minimum salvage comes from CT kills.

I Thought You Were Dead - Complete the campaign with Dekker still alive
Ha ha, memes! So far, it seems like this achievement is NOT awarded by:
- Loading into a post-game save where Dekker is alive and in your company
- Loading into a pre-1.3 save and finishing the campaign with Dekker alive and in your company
Current speculation is pointing towards this achievement requiring Dekker to be alive, in your company, and participating in the final battle to unlock. Thanks to Marowi for providing info on this. Assuming the unlock requirements work as expected, the best way to pull this off is to bench Dekker ASAP, avoid ship morale dropping as it may trigger an event in which Dekker leaves the company, invest in sim pods in the Argo to train him up, and putting him in the biggest, most heavily armored Mech you have for the last mission.

Just Getting Started/Dropping Like Big Metal Flies/That's a Lotta Salvage - Destroy 50/250/500 Mechs
These are inevitable if you play the game long enough, as they count Skirmish kills and kills across all your Campaign saves.

Killer of Light - Destroy 50 Light Mechs
Light Mechs are 35 tons and lighter.

Mass of Mediums - Destroy 50 Medium Mechs
Medium Mechs are 40 to 55 tons.

Heavy Metal - Destroy 50 Heavy Mechs
Heavy Mechs are 60 to 75 tons.

The Bigger They Are... - Destroy 50 Assault Mechs
Assault Mechs are 80 to 100 tons.

Surgical Extraction - Kill a pilot without destroying their Mech
"destroying their Mech" refers specifically to destroying the Center Torso. There's a couple of ways to kill the pilot without destroying the CT - While the simplest is to destroy the Head, that's not necessarily easy until later in the game. The more reliable method is pilot injuries. Non-lethal head hits, knockdowns, side torso destructions, and ammo explosions all inflict an injury on the pilot. Like yours, enemy MechWarriors have 3-5 injuries based on their Guts stat. Missile boats make MechWarrior takedowns easier, as the spread of impacts means you have more shots at hitting the Head than with energy weapons or ACs, and their high stability damage makes knockdowns more likely. If you have a missile-heavy lance, you'll likely get this by accident. If you somehow don't have it by late game, get a 10 Gunnery/10 Tactics MechWarrior, put them in something with +damage PPCs or AC/20s, and go pop the head off something with a Called Shot.
While the text of the achievement suggests legging doesn't work, since the pilot isn't necessarily killed, I wouldn't be surprised if it does anyways. Feel free to drop a comment if you got this by legging a Mech.

Alpha Striker - Destroyed an enemy 'Mech with an Alpha Strike
You'll likely get this without trying, since "use all your guns" has the highest potential damage, especially if you have a mech built for high alpha (MLas Vindicator/Hunchback are good early choices). Protip: If your mech only has one weapon, every strike is an Alpha Strike.

Kneecapper - Destroyed an enemy 'Mech's leg with a Called Shot
If you somehow don't get this by accident in the late-game, use a 10 Gunnery/10 Tactics MechWarrior and use a Precision Strike to either leg with enough damage to blow it out.

Look Out Below/On Wings of Flame - Destroyed 5/20 enemy 'Mechs with Death from Above
Goomba Stomp some Mechs. DFA hit chance is determined by Piloting, and damage can be increased with certain leg mods. Easy enough if as you're wrapping up a battle, you choose to DFA the stragglers.

Sock 'Em/Rock 'Em - Destroyed 5/50 enemy 'Mechs in melee
Like Look Out Below, but without causing your Mechs arbitrary leg damage. Melee hit chance is also determined by Piloting, and damage can be increased with certain arm mods. Again, melee near-death mechs as you clean up the end of a skirmish. If your melee mechs have support weapons equipped, make sure they're either toggled off or your melee does enough damage to destroy the CT, as support weapons fire after a melee and don't count as the melee for purposes of kills. DFA kills count as melee kills, too.

Stomp the Yard/Bug Stomper - Destroyed 5/50 enemy vehicles with melee
Same as Sock 'Em Rock 'Em, but easier since vehicles take double damage from melee, and more satisfying since stepping on tanks is hilarious.

Kick 'Em When They're Down - Made a melee attack on an enemy 'Mech that was knocked prone
You'll likely get this by accident while collecting your melee kills. If not... just... melee a prone mech.

Double Kill - Destroyed two 'Mechs in the same turn using Multi-Target
The same Mech has to score both kills in a single activation of Multi-Target. Since you can't use Precision Strike or called shots while multi-targeting, you'll probably want to engineer this by sandpapering down the target mechs with LRMs first.

Had Your Chance - Miss a Called Shot
This isn't to simply miss the location of your Called Shot, but to miss the Mech entirely. use Precision Strike with a MechWarrior with ♥♥♥♥ Gunnery, ideally shooting through cover at the extreme of their weapon's range band.

One Shot - Destroyed an enemy 'Mech's head with a Called Shot
This actually kinda sucks to do. Even with a 10 Gunnery/10 Tactics MechWarrior, your max chance to hit the head on a Called Shot is going to be 18%. All you can do is take every opportunity for Called Shots to the Head. Missile-heavy loadouts will help you get knockdowns to open up opportunities for Called Shots. Alternatively, if you max out your Morale on the strategy layer and put a Comms System in each of your Mechs, you can spam Precision Strikes instead, which is the more consistent way to take Called Shots. I recommend keeping at least one 10/10 MW in a Mech with an AC/20, so you can attempt Beta Strike whenever you see an Orion.

Beta Strike - Destroyed an enemy Orion with an AC/20 headshot
Hey, we were just talking about this! This achievement arguably sucks harder than One Shot, since you still need a headshot kill, but it has to be with a specific weapon (AC/20) against a specific Mech (Orion). It doesn't require it to be a Called Shot, so if you get a phenomenally lucky random Head hit, you can pick this up by accident, but you may as well take the Called Shots when you get the opportunity.

Highlander Burial - Destroyed an enemy light 'Mech with a Highlander Death from Above
Either play a Skirmish with jump-capable Highlanders, or acquire one in the Campaign and keep an eye out for Light Mechs. This is probably faster to do in Skirmish since you can engineer the circumstances you need. In either case, just give that Locust the old goomba stomp and call it a day.

Tis But a Scratch/It's Only a Flesh Wound/I'm Invincible!/We'll Call It a Draw - Removed one arm/both arms/both arms and one leg/all the limbs of an enemy 'Mech
If you've seen Monty Python and the Holy Grail, you know how to do this. If not, go get some culture. Precision Strike is your friend here - you may not want to try this until you have Comms System upgrades, because you'll be burning through a lot of Morale. Save one mech for last and go arm, arm, leg, leg. Doesn't matter whether you go left side or right side first, but I do believe you have to take down both arms before moving onto the legs. Obviously, you can't do both legs first as double legs kills the Mech.

This is the stuff that's specific to the campaign while not tied to the story.

Of Mercenary Mind/Work is Steady/Living the Mercenary Life/A Mercenary's Work is Never Done/Legend of the Periphery - Completed your first/10/25/50/100 mercenary contract(s)
Priority Missions don't count, so you'll need to farm up some work. Progression is tracked across campaigns.

Of Noble Heart - Negotiated for nothing but reputation in a completed contract
Take a contract, drop the C-Bills and Salvage bars to the minimum, and complete it. "nothing but reputation" is perhaps confusing wording, as you'll still get some money and salvage, just the minimum amount for the contract. This must be done on a contract for a Successor State, the Magistry of Canopus, the Taurian Concordat, or the Arano Restoration, as those are the factions you can negotiate for a rep bonus with.

Gimme the Goods - Negotiated for nothing but salvage in a completed contract
Take a contract, max out the Salvage bar, and complete it. This is a good idea for Defend Base and Assassinate contracts anyways, since you're likely to encounter lots of Mechs and valuable Mechs, respectively, on those types of missions.

5 Millionaire/10 Millionaire/Big Money, Big Prizes - Saved up over 5/10/20 million C-bills
You need to have the above amount of money at once in your Funds. The achievement pops as soon as you hit each milestone, so you don't have to keep it for any length of time. If you don't sell off salvage frequently and somehow don't have these by end-game, check your inventory: you likely have hundreds of jump jets, heat sinks, and stock weapons that can push you over the milestones.

Hope They Last/Who's Next?/Keep 'Em Coming/MechWarrior Factory - Hired 5/25/50/100 MechWarriors
This is another sheer numbers achievement. Replace MechWarriors as they die or get fired. Your starting team doesn't count. Progress is tracked across campaigns.

Deadeye/Danger Zone/No Guts, No Galaxy/Master Tactician - Maxed out a MechWarrior's Gunnery/Piloting/Guts/Tactics stat
Get a single MechWarrior to 10 of each stat. Going from level 1 to level 10 of any stat takes 28,500 XP. You can scum this if you really want to, but there's really no need. Unless you're terrible at keeping people alive, you'll get multiple 10-10-10-10 MechWarriors by the end of the game.

Top of the Crew - Your 1st MechWarrior to max out stats with 10s in all skills
Just get a 10-10-10-10 MechWarrior, 4Head. Easy if you have a post-game save before 1.3 - all of your MechWarriors' skills will be reset to what they started at and XP will be refunded. This will allow you to re-allocate them to a 10x4.

Tinkerer/Years of Sweat - Refitted 25/50 'Mechs
Since any change of loadout, as well as replacing destroyed IS, counts as a refit, you'll get this pretty quickly.

Saving the Metal! - Completed 25 'Mech repair work orders
This is any repair of a Mech that's taken structure damage. If you brawl a lot, you'll probably get this quickly. If you play a scout and 3 LRMboats, play a couple missions in man mode to speed this along.

Laser Show - Refitted a 'Mech with only Energy weapons
Very simple to do. If you do a repair refit on a Mech that already only has Energy weapons, you'll get this. Protip: It doesn't have to be a good loadout - 1 medium laser only still fits the criteria.
In 1.0.3, HBS "fixed an issue that trivialized completion" of these achievements, which might include one or both of the above methods. In this case, the easiest "legitimate" way to earn this would be to fill every hardpoint with the smallest weapon of its type, which for Energy would be the Medium Laser.

Raining Fire - Refitted a 'Mech with only Missile weapons
Same as Laser Show. The smallest Missile weapon is the LRM5 or SRM2.

Bullet Farmer - Refitted a 'Mech with only Ballistic weapons
Same as Laser Show. The smallest Ballistic weapon is the AC/2.

Punchmaster 6000 - Refitted a 'Mech with only Support weapons
Same as Laser Show. All of these are tiny.

Tank Up - Refitted a 'Mech with the maximum amount of armor
Armor is king, so you'll probably do this anyways.

Totally Awesome - Refitted a 'Mech other than an Awesome equipped with three or more PPCs
Keep in mind that this doesn't have to be a functional build. The mech can have no armor and overheat as soon as it fires, but as long as it has 3 PPCs, you're golden. This means you need to find a mech with 3 Energy hardpoints and 21 tons to spare. You should be able to fit this on the starting Blackjack or Vindicator if you strip them down.

Look What I Made - Built 10 'Mechs by collecting/salvaging their parts
Any combination of salvaging and purchasing Partial Mech Salvage will get you this, and it'll pop with the 10th Mech that you rebuild.

Fresh Off the Lot - Purchased a new 'Mech chassis
Some planets will have entire Mechs for sale, as opposed to the Partial Mech Salvage that you have to have three of to make a Mech. Just buy a Mech from one of these planets and it'll pop.

In Over Your Head - Retreated once from a contract before any of your 'Mechs got destroyed
Hit that Withdraw button in the corner of the screen once you've started a mission. Unsure if you need to enter combat first.

One 'Mech Army - Successfully completed a contract using only one 'Mech
This can be done easily early on, and hilariously probably easier in mid-game, all with the humble starting Spider. Take the Spider, max out its jump jets and armor, and add a Hit Defense Gyro if you have one. Put in your highest Piloting MechWarrior, and solo a Recovery mission. You're going to be abusing the defensive power of Jump Jets - once you are in range of enemies, jump into the zone (or as close as you can) and Brace. Depending on the Piloting of your MechWarrior and the quality of your gyro, you'll tank the enemy's one turn of fire with as high as a -45% chance to be hit, and 50% damage reduction on anything that does. After you've loaded the VIP, sprint towards the evac point. You should be able to make it out of range in a single turn.

Complete Roster - Acquired all 36 launch date 'Mechs
Hope you like PokeMech! The Mechs you have to collect are:
Light: Locust, Commando, Spider, UrbanMech, Firestarter, Jenner, Panther
Medium: Cicada, Blackjack, Vindicator, Centurion, Enforcer, Hunchback, Trebuchet, Griffin, Kintaro, Shadow Hawk, Wolverine
Heavy: Dragon, Quickdraw, Catapult, JagerMech, Thunderbolt, Cataphract, Grasshopper, Black Knight, Orion
Assault: Awesome, Victor, Zeus, Battlemaster, Stalker, Highlander, Banshee, Atlas, King Crab
All you need to have is any one copy of each Mech, as opposed to one of each variant (which would involve hunting down 59 variants, and would suck). You must have every Mech in your possession, either active in the Mech Bay or in storage, at once for this to pop. You start the game with a Blackjack, Shadow Hawk, Vindicator, Spider, and Locust, and will be granted a Centurion As far as acquisition goes, remember that enemy Mech tonnage increases based on milestone Priority Missions. This does mean that you'll need to play the Restoration campaign to gain access to every chassis, and will probably need to do a fair bit of grinding unless you're godly at beheading Mechs. For easiest collecting, I'd recommend you make sure you've collected every Light Mech before starting First Strike (except the UrbanMech, which is only found in stores as of v1.0), and every Medium Mech before Liberation: Smithon.
This achievement seems to currently be buggy for campaigns started before the 1.0.3 patch. A potential fix seems to be readying all Mechs that were in storage before the 1.0.3 patch and returning them to storage. You may also need to salvage/purchase another Mech to trigger the achievement. Thanks to Zloth for sleuthing out this fix.

These are achievements specific to Career Mode, the game mode added in the Flashpoints update.

Survived A Mercenary Career - Completed your first Career Mode campaign with any rank
Career Mode lasts 1200 in-game days. If you manage to make it to the end without going bankrupt or, presumably, dying, you win! Good job.

A Veteran Mercenary/An Elite Mercenary/A Legendary Mercenary/A Career Unheard of in Over Two Centuries - Accomplished a Career Mode score at Veteran/Elite/Legendary/Kerensky rank
Career Mode is also scored when you finish, it's currently unclear whether you receive a score if your career ends prematurely or if you have to ride out the entire 1200 days, but for the higher scores you'll likely need to use every day of it anyways. The minimums for each tier are:

Veteran: 320,000 points
Elite: 480,000 points
Legendary: 720,000 points
Kerensky: 784,000 points

As of Patch 1.3, it seems that it is currently impossible to obtain a Kerensky rank as the upper limit of Career Mode scoring is 770,015. Thanks to Marowi for reporting this.

These are the achievements for allying with the various factions of the game world. They're all very simple and boil down to "do missions for the faction, don't work against them, hit 100 reputation and hit Ally With Faction", so each individual achievement which I'm including for perfectionism's sake will likely include humorous anecdotes or Battletech lore. If you played a lot in post-game before Patch 1.3, it's possible you'll be able to load that save and ally with multiple factions, since reputation losses were insignificant compared to the amount of reputation gained, especially if you chose to forfeit part of your pay.

Indomitable Will - Become Allied with House Steiner
House Steiner is the northwestern-most faction of the Inner Sphere, or at least on maps of it (do cardinal directions exist in space?). They specialize in beautiful blonde boys, big guns, and big mechs, with 4 Atlases referred to as a "Steiner Scout Lance". They also are fond of cheating, with the last boss of MechCommander 2's campaign being a Steiner Colonel who pilots a jump-capable(???) Atlas. I'm aware that the Atlas can be fitted with Jump Jets in HBStech as well, but it was dumb then and it's dumb now.

By Freedom's Sword - Become Allied with House Davion
The Federated Suns position themselves as champions of freedom and liberty, but House Davion managed to turn a democratic government led by a President into a constitutional monarchy with House Davion at the head. Ironic, huh?

One Vision - Become Allied with House Liao
I guess this is the house motto of House Liao, but all I can think of is the (much better) "KANE LIVES" cutscene from Tiberian Sun. Man, too bad Westwood isn't around anymore.

Honor The Dragon - Become Allied with House Kurita
Wait, really? The Draconis Combine, whose emblem is a dragon, has the house motto of "Honor the Dragon". I'm surprised FASA had the restraint to not call them House Ryujin.

We Stand United - Become Allied with House Marik
The actual (relative) champions of freedom in Battletech, and also the George Harrison of the Inner Sphere.

Hail to the Queens - Become Allied with the Magistracy of Canopus
Remember this faction? The one that ostensibly bankrolled the events of the campaign? Me neither.

Loyal to the Periphery - Become Allied with the Taurian Concordat
Remember this faction? Ostensibly the bad guys, with Space Adam Jensen? I pretty much only remember Space Adam Jensen.

Yar Har Fiddle Dee Dee - Become Allied with Pirates
BEING A PIRATE IS ALRIGHT WITH ME! DO WHAT YOU WANT CAUSE A PIRATE IS FREE, YOU ARE A PIRATE!
Keep in mind that basically every faction hates Pirates, so don't expect to go for Kerensky rank in the same Career Mode run in which you do this.

Rookie/Seasoned MechWarrior/Grizzled Vet - Played 5/50/100 online multiplayer matches
Play a lot of Battletech multiplayer. I don't have anything clever or insightful to say about this.

Good Start/Champion in the Making/MechDominator/Legendary MechCommander - Won 1/25/50/100 online multiplayer match(es)
See above. Hope you like playing scout/LRM boat lances? I guess?

Try, Try Again - Lost 10 online matches
Again, nothing insightful here. I believe you have to actual play and lose instead of just disconnecting, so... lose fast?

Eck's Gon' Give It to Ya - Battled someone who has this achievement (and therefore has either battled HBS developer/BT tourney champ Chris Eck or battled someone who battled someone...who has)
Convince Chris Eck (@Eck314 on Twitter) to play me (@Serothel on Twitter) in Battletech, DM me after the game, and I'll spread this achievement to you.
P.S. Harebrained, you get a pass because the name of this achievement is great, but viral achievements are dumb.

These are achievements that, while possible to do "legitimately", are most easily cheesed through single-player Skirmish and custom lances. Since you're reading a 100% Achievements guide, I'll assume you're willing to do the latter, although I'll include brief thoughts on the former where relevant.

Getting the Hang of It/Champion of the Arena - Won 50/100 Skirmish matches
This is... grindy. If you want to take this seriously, I suppose you could use the 100 matches to experiment with different lance compositions and learn the nuances of the various maps. Or, you could make a lance that stomps on a relatively powerless OpFor lance and grind these out mindlessly while catching up on or starting a new TV show. I recommend Brooklyn Nine-Nine by virtue of "it's hilarious".

Who's Unbalanced? - Won a skirmish match using fewer 'Mechs than the AI opponent
Man-Mode: Field Mechs that you're good with that have an advantage over the OpFor's Mechs, whether it be range, raw damage, whatever works for you.
Easy Mode: 3 Atlases vs. 4 Locusts is still a 3v4.

Plague of Locusts - Won a 4v4 match with all of your 'Mechs being Locusts
This achievement is ambiguously worded, but thanks to user X-Juvenal89 we know that your mechs must be Locusts, but the OpFor lance doesn't have to be. However, the easiest thing for a Locust to kill is another Locust, so there's no sense doing anything but 4 Locust vs. 4 Locust.
Man-Mode: There's a couple ways to go about this. With stock mechs, you can try the LCT-1M and keep the others ranged, but you have limited LRM ammo and minimal armor. What's probably easiest is to make the enemy Locusts LCT-1M, use the 1V or 1S configuration for your own Mechs, and get up close and personal.
Easy Mode: Make a trash Locust variant. MechLab won't let you make a Mech with 0 armor in any location, so give it 5 armor everywhere. It also needs a weapon, so give it one Flamer (flamers plural are dangerous, flamer singular is trash). Use any of the stock Locusts (or your own variant, I prefer MLas+3SLas) to steamroll them.

Atlas Shrugged - Won a skirmish match with an Atlas vs four AI Commandos
Man-Mode: This is actually really hard, and while I won't say it's impossible, I'm not sure that it's possible with stock Mechs. 4 stock COM-2Ds will kill your MechWarrior through head hits before they breach your armor, and while there's less risk with COM-1Bs, damage from those lasers can add up. I'd recommend going against the 1Bs. For a mid-tier challenge, remove the SRMs from the 1Bs and replace them with lasers or more heat sinks so they're still dealing damage but have a lower chance of killing your MechWarrior, and run an LRM-heavy Atlas to abuse knockdowns and injuries.
Easy Mode: Make a Commando variant with one Flamer and minimum armor. Laugh as your Atlas eats a Commando every turn.

Age-Old Question - Won a skirmish match with three Commandos vs an AI Atlas
Man-Mode: As mentioned above, the COM-2D model is your friend playing stock due to its SRM-heavy loadout. You should keep running to keep evasion stacks high, preferably ending moves in cover or out of LoS.
Easy Mode: Make an Atlas variant with one Flamer and minimum armor. If you think you know how the rest of this section of the guide is going to go, congratulate yourself on being super right. Burn the Atlas down by whatever method you prefer, but keep your distance. It may not have guns, but its melee will still oneshot one of your Commandos if it hits CT.

The Deadliest Catch - Fielded a lance of four King Crabs, won, and lost no 'Mechs
Man-Mode: King Crabs are slow but powerful, and the bulk of their output comes from the double AC/20s. Make sure whatever lance you go up against doesn't outrange you. Watch your heat and ammo as well, as the AC20s have limited ammo and run hot.
Easy Mode: 4 King Crabs vs. 4 Locusts or any Light lance. Cackle maniacally as double AC/20 hits oneshot Lights.

The Trashmen Cometh - Fielded a lance of four UrbanMechs, won, and lost no 'Mechs
Man-Mode: You'll be hard-pressed to find a similar BV lance that 4 Urbies can take down with no losses. The AC/10s can do some heavy damage, but your limited ammo means every miss is painful and the Urbie is basically useless once you're out. Good luck!
Easy Mode: mike_hanna211 reports that this achievement requires the enemy lance to have 4 mechs, so dunk on some Locusts.

Making the Most of What You've Got/Undaunted/Fortune Favors the Bold - Won a skirmish match with a Lance Value 15m less than the OpFor's
Man-Mode: It's going to be tough to do this at higher deficits, as a greater LV divide means you're increasingly outnumbered and/or outgunned. I recommend you curate this fight by creating a lance that can exploit the weaknesses of the enemy lance and play to your strengths. Frustratingly, despite being a (theoretically) escalating challenge, completing a match at a 15m deficit does not unlock the achievements for 5m and 10m LV deficits. Be prepared to do this 3 times, and adjust your lance composition(s) to each deficit level.
Easy Mode: All of that stuff, except you'll be exploiting the fact that Assault Mechs have extremely high BV even with few or no weapons attached.