Pep up quests are easy to do. You just place the pepped up characters on the reserve then switch them in when you face the enemy.

The casino related quest on Act 2 is the most annoying and it involves the roulette. You need to abuse the auto save for it. The quest say the reward that they will give but no, outside of the costumes on the exchange shops, you can skip them.

I don't like Pep up quests that require me to use characters that I am not using and requiring skill's that I don't care to learn.

It's still a pain to just randomly fight until they decide to finally pep themselves up which could take a while.

It's honestly just a hassle and not worth the effort. Glad to know I can just safely ignore them then.

You have at least 1 of those pep up quests that gives a recipe so you'll have to check. I believe the Wild Side one was one of them. You don't care about getting all achievements anyways I assume.

None of the side quests are missable. They may be unavailable at some points in the game but by Act 3 they will all be available again. If you wait that long to do them some of the rewards might not be as useful to you though