Final Boss: M1 with about 400 ammo, Minigun with 1000 ammo and 20 grenades. When it appears, fire at it with the Minigun, and when it overheats, switch to M1. When it gets close enough for grenade range, spam all 20 grenades while firing the Minigun again. It's really easy.
Badges were so easy: Chose Redzilla, Raised Power to about 200-300, then maxed out speed using +2 in-training items. Had 500pow/200def/500spd/100int, and sweeped all the bosses in two turns.
Defeat 50+ HP monsters: Lemure and explosion. Set 4/9 Lemure, and then explode him dealing 28 damage. It will be reborn as a Scrambled lemure as 3/9 and you can blow him up again.
Terrific game with cool visuals and gameplay. It was interesting and refreshing to the countless zombie games lately. My only complaint is that there could have been a slight twist on the quests that are given, like certain boosts or something.