First thing to consider is how the AI acts:

• AI will fire weapons based on the weapons groups. Place all weapons in one group and the AI will alpha strike for every attack.
  
• Because the AI will cycle through the weapon groups, the first weapons group ends up being the primary weapons group.
  
• They will fire weapons based on weapon group availability to fire. If the target is out of range or the weapon is on cooldown, they will not fire the weapon. If the SHORT range weapon is available to fire before the LONG range weapon, they will move in to fire said short range weapon. This means LRMs may rarely get used. Group and pick your weapons accordingly.
  
• They will fire their weapons based on heat status. Too much heat and they will not fire. So placing all the weapons in one group is not efficient as the AI has to wait until heat level is low enough to fire the weapon group again.
  
• The AI will move to an ideal weapon range of each weapon. This means they will move close for SRMs and Medium Lasers, but move farther for PPCs and AC5s and potentially out of range of the SRMs and Medium Lasers. This will lower the AI DPS because they may spend precious seconds walking back and forth to the enemy to get into weapons range. Consider your loadout with this in mind.
  
• They will not recognise chain fire. So organise your weapons group with this in mind in regards to range and heat. Example: Instead of grouping 3 PPCs into 1 group, split each PPC into it's own group so at least 1 fires when the heat level permits.
  
• The AI are actually crackshots. This means high damage, high velocity, point damage weapons are the ideal weapons. These are lasers, PPCs and autocannons.
  
• Speed is life. The AI fully takes advantage of speed and the faster they move, the less likely they will get damaged. They take so much advantage of it that they seem to immune to the negative effects of Motive Equipment and will run them forever at max capability. Yes this means a Dragon-SDW and Gladiators outrunning light mechs.
  
• OK maybe there's such thing as too much speed for AI. If the AI moves to fast, say over 120km/h, they might run into terrain as it's pathfinding can't keep up. So there's a chance they get caught on a rock or something and take a face full of weapons fire as they struggle to wiggle their way out.
  
• AI is bad with jump jets. While they can perform Death from Above and DfA is sometimes considered the last "weapon" available preventing ejections, they actually end up as slow moving targets. These can be safely removed.

These weapon considerations are for general purpose lancemates. They will see you through nearly every misson. The best weapons for this purpose have the following characteristics:

• Point damage to focus damage on a part instead of spreading it all over the target.
  
• Medium to long range (450m+) so they start shooting the moment the enemies enter sensor range.
  
• Low heat so they maintain the high rate of fire.
  
• Light enough to mass at least 2 of them for primary weapons.
  
• High rate of fire to keep up the DPS. Minimum over 10 RPM.*
  
• Sufficient damage per shot.*

What this leaves you with is lasers, autocannons and PPCs and in that order. The points with an * are essentially asking you this question: How fast can your AI destroy the center torso, the most heavily armored part, of an enemy mech. Since MW5 sends waves of lances at you, it is in your best interest to kill them as fast as possible even with terrible shot placement. A tier 1 Large Laser - SB does 7 damage and fires 14 times in a minute for a potential damage of 98. That's enough to core out a 50 ton medium mech with max armor in a minute (assuming every shot hits the torso). Since the damage for these weapons type is 7-12 (until Clan weapons), the only significant way to increase damage is adding more weapons or increasing rate of fire. That's why having the ability to have at least a pair can improve AI performance.

• Clan Large Pulse Laser
  
• Clan Large ER Laser
  
• Clan Medium Pulse Laser
  
• Clan Medium ER Laser
  
• Large Pulse Laser
  
• ER Large Laser - SB
  
• Large Laser - SB

Most Lasers end up being the preferred weapons due to balanced damage, light weight and rate of fire. Most. You will notice the Medium and Large laser missing from the list and that is because the Medium Laser's lack of range and the Large Laser's rate of fire and laser duration.

The Medium Laser brings the enemy and AI too close to each other. Not only will the enemy aim improve, but by forcing your AI to use weapons with a longer range, they will move out of the range of short ranged weapons. With most 3025 mechs spamming SRMs and Medium Lasers, this will reduce the amount of time AI mechs spend in the repair bay.

Large Lasers have good damage but their rate of fire is painfully slow and the laser duration exposes them for too long while allowing the enemy mech to spread the damage by simply moving. That being said, these weapons become viable if you invest in the Laser cooldown and duration upgrades. Since those upgrades are expensive and time consuming, they may not be best option for many mechs.

• All Clan 20 class LBX/UAC
  
• All Clan 10 class LBC/UAC
  
• All Clan 5 class LBX/UAC
  
• Clan Gauss Rifle
  
• All IS Class 10 LBX-SLD/AC except RF models
  
• All IS Class 5 UAC/AC except RF models

The reason autocannons are preferred over PPCs is because the rate of fire and lack of heat to maintain that rate of fire. Though ballistic weapons are heavier, energy weapons require more heat sinks to maintain a similar rate of fire which negates the weight advantage.

Inner Sphere AC20 isn't on the list because of it's low rate of fire, slow projectile speed and short range despite it's great damage. While human players can ignore the range limits, the AI cannot. That being said, the ballistic range, velocity and cooldown upgrades not only make the AC20 viable, but incredibly deadly. With the maximum upgrades, the AC20 almost moves as fast as an AC10 and this will have your lancemates landing a lot more head shots. This is actually my preferred AI King Crab setup and a full lance of these turns high difficulty missions into head hunting and limb removal operations. Inner Sphere Gauss Rifle suffers similar problems as IS AC/20 while also being heavier. With upgrades, they're more viable for AI use but generally an LB 10-X is better.

For Inner Sphere LB-X cannons, SLD versions are preferred over the regular version because each individual pellet is not that strong compared to Clan pellets. Burst Fire (BF) versions can work and the LB 10-X BF does as much damage as a Gauss rifle so long as the projectiles all hit the same part which can be helped with velocity upgrades. LB-X are the preferred cannon because the AI doesn't really take advantage of the UAC force fire function. ACs are heavier and run hotter in comparison to both making them the worst option. AC-Rapid Fire options are great for human players, but perform poorly for AI because they will burn through ammo quickly. AC/10-RF would make the list only if the chassis has space for the ammo, but you probably get a lot more mileage out of regular AC/5 which has double the ammo per slot for the same damage albeit lower RoF.

Rifles have too low of a RoF for AI to take advantage of despite the damage. Conversely, class 2 autocannons of all types have too little damage. Good for humans, not for AI lancemates.

• Clan ER PPC
  
• PPC
  
• ER PPC

PPCs are great and are better than autocannons in certain circumstances. They have a decent RoF, do significant point damage, never run out of ammo and don't have explodey ammo. But in the hundreds of simulations I ran, PPCs underperformed compared to Large Laser-SB because the heat they generated hampered the RoF. Even with more heat sinks, the Large Laser-SB would simply benefit as well because you would be able to group fire them instead of splitting them individually into groups. This means the lasers would act as one weapon surpassing the damage of a PPC. Also if the PPC misses, it misses. With lasers, there is a chance the AI can go back on target. Even if the laser spreads the damage there is at still some damage instead of a complete lost shot.

ER PPCs are arguably worse than PPC because of the heat it generates while having the same RoF and damage. Most maps will not take advantage of the extra 500m. The Clan ER PPC, on the other hand, is a clear upgrade and one of the best weapons.

Marauder MAD-3R

• Weapons Group 1
  1 x Large Laser - SB (RA)
  
• Weapons Group 2
  1 x Large Laser - SB (LA)
  
• Weapons Group 3
  1 x AC/10 (RT)
  
• 2 x AC/10 ammo (RL, LL)
  
• 4 x Single Heat Sinks (CT)
  
• Max Armor on everything except leg (59 each)

This is a basic 3025 era mech that the AI can use well. As time moves on, it will scale well with Lostech and Clan versions of the above equipment when they become available.

Maintain spacing, stay within range.

This loadout is for close combat or where trading blows with the enemy is unavoidable. The build is simple:

• Fast mech to avoid damage, get close and flank.
  
• Max armor. Damage will be traded.
  
• Spam PPC-X, all Medium Laser types, all Small Lasers types and SRMs. Still mind the heat and weapon groupings.

The name of the game is fire as many weapons as possible consistently and without shutting down. Under 400m opens up nearly every weapon in the game to fire so your AI lancemates must out DPS your enemies. A very important but much looked over function at this range is facing.

• How fast can your AI mech torso twist to face the enemy so it can bring it's weapons to bear.
  
• How long will your AI mech face the enemy and in turn receive a face full of return fire.
  
• How long will your AI mech focus on an enemy exposing their rear to enemy teammates. At this range, there aren't many places to run.

This is why short bursting lasers and non-ST SRMs are preferred for torso hard points to reduce the amount of time the AI will stare at an enemy. This is also why most light and medium mechs will excel with this build because the running speed and torso twist rates are much better than heavy and assault mechs without the torso twist and speed boost upgrades. Keep in mind, facing time also includes lock on weapons.

Streak SRMs are decent weapons and the AI can actually employ them well especially when Elementals arrive on the battlefield. Just keep note that regular SRM and the Artemis versions will fire faster and disengage faster at the cost of accuracy since they don't require lock on. It is highly recommended to not use the Stream (ST) versions because the missiles move too slow for AI to compensate and will miss a lot while increasing facing time. This will leave you with the regular versions that will have wider spread which will spread the damage but any damage is better than no damage.

Larger launchers will have a wider spread while also reloading slower so it is recommended to carry or group the same size launchers if possible. SRM2s will be ready to fire much faster and spread less so if you have the hard points, spam them. Artemis SRMs are not worth the additional weight. At the range these SRMs are being fired, the spread improvement is negligible.

Since the weapons at this range have specific quirks, it is recommended that the same weapons are grouped together. Medium Lasers with Medium Lasers, Small Lasers with Small Lasers, SRMs with SRMs, etc. Also it is wise to separate torso and arm weapons at this range since arms move faster and have a wider field of fire than the torso. This will allow arm weapons to fire first instead of waiting for the torso to line up.

Kintaro KTO-18

• Weapons Group 1
  2 x Medium Laser - SB (RA, LA)
  
• Weapons Group 2
  1 x SRM4 (LA)
  
• Weapons Group 3
  2 x SRM4 (RT, CT)
  
• 2 x SSRM ammo (RL, LL)
  
• 6 x Single Heat Sinks (HD, CT, RT, LT)
  
• Max Armor

This build works from 3015 and can be upgraded with Lostech and Clan equipment as the technology becomes available. Lostech introduces double heat sinks and SSRM2s. With the 4 missile hard points on the Kintaro, SSRM2s can be spammed to be effective but SRM4s might still outperform depending on circumstance. Clan tech will allow 4 Clan SSRM4s to be installed and the Medium Lasers can be replaced with Clan Small ER Laser for the low heat penalty but similar range and damage. One might be tempted to spam SRM6s but the heat penalty will affect the rate of fire. While the total damage output would work against a single opponent, MW5 launches multiple lances at you so your AI companions don't have the luxury of waiting around. This is one of the reasons why the Wolverine is one of the most effective vanilla mechs for AI because the total heat generated from it's weapons can be handled by it's heat sinks.

Get'em!

So you want a LRM lancemate launching warheads on foreheads, eh? If you don't want to baby the AI by telling them where to stay, remove all short range weapons and give them long range weapons so they will automatically maintain distance (200m+) for LRMs to fire. We're talking PPCs, AC/5s and even AC/2s. Clan ER Medium Lasers are a godsend for these. Alternatively, the inclusion of Clan and Hot Launch LRMs which have no minimum range allows you to have a mech purely armed with LRMs and not worry about distance.

The AI tends to do better with regular LRM instead of Stream versions mostly because Stream requires a longer lock on period. If a perfect lock on is maintain, Stream will outperform regular launchers but not by much so it's not really worth it. Artemis versions of either are very effective and worth the additional weight.

The only other thing to note is LRM 15 is the most efficient launcher among Inner Sphere LRM launchers. Something to consider when choosing between the LRM 15 or 20 because the 3 ton difference could be used for heat sinks or ammo. Technically the LRM 5 is the most efficient by reloading faster and saves more weight than the LRM 15 but there aren't mechs with enough missile hard points to take advantage of this. All Clan missile systems are great so doesn't matter what you use since they function like a bunch of LRM 5 launchers.

Fire for effect

Bleeeurgh! The result of eating 400 LRMs

Heat plays a huge part in Mechwarrior as much as it does in it's tabletop counterpart, Battletech. Funny enough, if you know how to heat works in Battletech, you can use that in Mechwarrior as they're pretty close. This will help you determine how many heat sinks you need to maintain a decent RoF for your AI lancemates. I prefer this method instead of using MW5's numbers because they result in way too many heat sinks.

Important notes:

• In tabletop Battletech, all mechs must have at least 10 heat sinks. In MW5, you are allowed to go below this threshold in some mechs but it is not recommended unless you know heat sink to heat generated by weapon ratio.
  
• All Inner Sphere mechs are designed with at least 10 single heat sinks. This is represented as Heat/s rate of 1.0.
  
• All Clan mechs are designed with least 10 double heat sinks. This is represented as Heat/s rate of 2.0.
  
• You can find out the heat sink to heat generated by weapon ratio by going on https://www.sarna.net/wiki/Category:Weapons and looking up the heat generated by the weapon on tabletop. For example: The Large Laser generates 8 heat on tabletop. If you put 2 of them on your mech, they will generate a total of 16 heat. With the 10 single heat sinks that should already be in your Inner Sphere mech, this means you need an additional 6 single heat sinks to negate it's heat or 1.6 Heat/s in MW5. This is not a perfect calculation since environment, upgrades and weapons grade also factor in.
  
• Also factoring in is the heat generated by your mech's movement. In tabletop, walking speed generates 1 heat and running generates 2 heat. Since in MW5 everyone is running all the time, it's safe to assume that you need an additional 2 single heat sinks or 1 double heatsink to be heat neutral.

As you can see, weapons like the PPC lose their weight benefit with the more of them you add. Each additional PPC requires 10 single heat sinks or 5 double heat sinks to negate it's heat and maintain efficient rate of fire. This matters because unlike a human player, the AI will not pick and choose which weapon to fire or ignore and will simply cycle through weapons groups and fire whatever is available.