Jean Grey
There’s already a pretty solid offering of X-Men characters in Ultimate Alliance 3, but with even more on the way, Jean Gray seems like a surefire pick, maybe even in her Phoenix incarnation. Jean has consistently been shown to be one of the most powerful Mutants in the entire Marvel universe, and she’d be a great addition to any dream-team of heroes.
Here telekinetic powers would make her entirely different from any other character on the roster, maybe even having the ability to pick up and throw enemies. She could also work as a ranged character like Magneto, drawing enemies into groups with her telekinesis, in order to set them up for a combo from another hero.
Considering Jean Grey was already featured in Ultimate Alliance 2, she’s a natural addition to the roster of The Black Order.