This strategy was used on normal mode. I do not know how much harder or easier the fight is on the other difficulties.

The team I used for this fight is shown here.


Klein, Nyx, and Io are the mogs you're going to need. They don't need to be level 99 but by this point in the game all characters are going to be at minimum level 90. I had also completed all the belt challenges in the sewers, so if you haven't done those they should be pretty easy. This strategy does not require any skills bought from the shop in Carona woods and I've beaten Peppy Jack without using them, although the skills "ESP Rockin'" and "White Thicket" can help.

As for your Xoth alien buddy, the transformation I used the most was Tiny Nyx, although if everything else in the strategy goes smoothly you may not need much of the alien's help. Having transformations that have big damage or reviving abilities can also help.






Lastly, make sure you have plenty of healing items, beat restoring items, and especially pocket defibs. Klein is extremely important in keeping the team alive so having means of keeping her up is vital. Elemental items aren't needed.

Peppy Jack basically has two moves. An attack that will nearly one shot your entire party and an attack that will one shot one person. Brute forcing won't work, as the boss deals way too much damage to both be healing and attacking at the same time.

The solution? Reduce Peppy Jack's ability to attack as much as possible.

Klein and Nyx are the two that will keep the party alive as much as possible. The first couple turns will be a bit rough since you won't have the buffs up but you should start the battle fully healed and able to tank about one hit. Before you begin attacking, Klein should use "Cat's March" at the start to ensure nobody gets one shot by Peppy Jack before they get to take their turn. Nyx will use "Freezing..." repeatedly until Peppy Jack is frozen. Eve will defend or being the one using items and Io will use "All eyes on ME" to make sure she doesn't get one shot. On turns where Klein does not need to heal anyone or speed buff again, she should use "Steel Screech" to give the party a chance to survive should they get hit by Peppy Jack. Remain on the defensive until Peppy Jack is frozen.

Made it without dying this far? Good. After Peppy Jack is frozen, him unfreezing takes up a turn, so you have a warning before he attacks again. Attacking Peppy Jack unfreezes him faster, so spend a turn or two preparing buffs or using items before attacking. Some notable skills to use in preparation include: Have Eve use "Double Up" on Klein or "Settle Down!" on the boss, have Io use "SPICY!", and have Klein use "Steel Screech." While I did not use it during my run, Nyx's move "White Thicket" that can be bought from Zhengy is also useful for reducing the boss's defense. If Peppy Jack unfreezes while you're not ready, revert back to step one.

Peppy Jack has a whopping 5000 health and no elemental affinity, so how are we going to do enough damage? At this point all that's been done is Nyx freezing Peppy Jack and maybe Io has been able to get a couple hits in. Our main source of damage is going to come from Eve and Io. By this point in the fight, you should have 100 Heart. Change Eve's element to fire. Have Eve and Io use fire moves and try to inflict burn on Peppy Jack. Try to save your 100 Heart attacks for Io to use, as her ultimate attack has an extra burn chance on it. If you don't already know, burn inflicts percentage damage per turn. Peppy Jack's strong defense can't do anything against 10% damage per turn. Should you inflict a burn, it will do 500 damage per turn, way more than if you had each character attack normally. If you don't inflict burn, don't worry, the defense debuffs that Eve and/or Nyx inflicted back in step 2 should boost your damage to reasonable levels. Klein and Nyx can attack as well, but should be on item duty to make sure everyone's Beat is at a stable level. This strategy can take awhile, it all depends on when you inflict burn. In my run I got burn very late into the fight but still managed to beat him in about 10 minutes and on my first try using this strategy. (In total I took about 40 minutes trying to defeat Peppy Jack. Only on the last run did I try to freeze and burn him.)

Should everything go correctly, you should have Jack burnt to a cheesy crisp!

If you get enough attack debuffs from Klein on Peppy Jack, you may be able to attack him with him unfrozen, as he'll do little enough damage that Klein can safely heal the party without anyone in threat of being one shot. Eve has a move that you can purchase from Zhengy called "ESP Rockin'" that has a chance to burn, circumventing the need to change Eve's elemental affinity. I did not use this skill during the fight however, so it is not required. You can also try similar strategies that involve disabling Peppy Jack wherever possible, such as using Kon's pheromones, but going "Half-Cold, Half-Hot" was what worked for me.

• The Denim Blade for Klein
  
  
• One happy booby lady
  
  
• An achievement
  
  
• A secret code if you have the soundtrack
  
  
• An expansion pack of gacha cards that Xiu can give you
  
  
• Chibi Chee and Tiny Oni Tony DNA if you show Chee your mogs
  
  
• And a sense of pride and accomplishment.

Hope this helps, and please thumbs up if it did!