[Annuga]

I do like risk VS reward final forms, so I'll look at the final forms, including other comments in general
Ultimate: Become evil unless Gary Stu, become OP AF
Shining: Solar Power
Survive: No real reason, but given the series, make sense that you'd use this as much as possible
Blaster: Can't remember
King: Risk becoming an insane bloodlusting Undead for incredible power
Armed: You risk losing your oni powers
Hyper: Fuck you I'm Tendou Souji
Liner: Character Development solidified, and was needed so Ryutaro could fight with more than Mamotaros iirc
Emperor: Spammed only because the suit actor had difficulty with the other suits
Complete: don't remember
Extreme: Character development and slowly kills Philip
Putotyra: Stupidly strong, but risk going beserk
Cosmic: All Powers Combined but if your friends want to things without you it doesn't work
Infinity: Mana I guess?
Kiwami: Becoming an Overlord with godly power
Tridoron: Symbolizes the partnership between Shin and Krim
Mugen: HOOMINZ HAEF EENFINUT POTENSHUL