He's ripped. And a ninja. And comedy relief. Also he's a ninja. And a ninja. And a nail. And has a Nox Nyctores he doesn't realize he has. Bang also loses most of the time if I remember correctly.
Tsubaki already knew about Izayoi, so it would make sense she would understand how to use it, in addition to her academy training. She also constantly loses, being the Garbage Lady according to Hazama. Platinum has the soul of one the Heroes and has a staff that can create matter. I don't see the problem in her fighting.
Marvel is a completely different game and setting. We're not talking about its semantics.