The trick involves having a Thief to steal the enemy's equipment, otherwise you will be at a disadvantage. Nemesis Mk-II gives the Prinny approximately 13,000+ stats in everything except ATK, which will be about 31,000. Prinny Suit gives him about 45,000 HP and 22,000+ DEF and RES. It will be easier if you can steal it. If you fight Prinny Baal with no "Stronger Enemies" bill passed, your Thief should be about level 3000+. When fighting him at level 9999 (maxed out "Stronger Enemies"), your Thief must be about level 5200+. Also, you should have extra humanoids that can be used as sacrifices. You also need your "damage dealers" crew. It would usually consist of Divine Maijins (level 4000+ recommended) and Larharl having over 1 million ATK and 600,000+ HIT (any level as long as you have those stats). You are going need some top items to boost your stats. Level 100 super robo suits equipped on Larharl and level 100 Yoshitsuna should suffice. The Divine Maijins should have the most damage dealing equipment you have in your disposal. Optionally, Flonne should also have Braveheart at a decent level with major INT stats. Start by summoning your Thief to the battlefield. Move him in front of Prinny Baal, and use one of the stealing hands (Dream Hand, Bandit's Hand, Stealing Hand, etc.). Usually the cheaper hands work just as well as the expensive ones. Steal Nemesis Mk-II first. Once you have executed this command, summon one of your disposable humanoids to lift the Prinny. This requires 8+ Movement to go on the sides of the Prinny. Then, end the turn. If done correctly, the Prinny should have used his turn killing the humanoid that lifted him. Next, steal the Prinny Suit. Summon your damage dealers and Flonne. Have Flonne use Braveheart to increase the ATK stats of all your damage dealers, then have the damage dealers execute their strongest "single" special (one that only attacks one enemy for high damage, such as Nightsever, Avalanche, etc.). Before you end this turn, have another disposable humanoid to lift the Prinny, and then end the turn. Repeat this until Prinny Baal is defeated.