He's not useless, he just has a bad match-up with Devana or whatever her was name. There's literally nothing he could have done when she put the bombs on him, and he didn't know what her power was.
Deryl would actually be way better suited to fighting Evander (the male twin) than MC was. Remember, all that guy has is that whatever his body disintegrates or something, but energy, like Met's lightning, can still hurt him. Deryl has that plasma gun, and he can fly. He could literally just fly around shooting Evander and he wouldn't be able to do anything about it.
MC can't really do anything to Evander because he has no energy attacks, but he's really well-suited to Devana because her bombs don't do anything since he can just shapeshift out of them, and he seems much stronger than any monster she can summon. From what we've seen of her, she's basically useless against the MC.