This concept is really silly anyway. Like RWBY is just weird to have.
I personally have a wish list of characters I would want to see in this game. I'm not too exciting for the 4 series because they will all most likely be super predictable pics.
personally if there is one character I truly want, it's Ryuko from Kill La Kill. That's the character I want the most (Most because I am pissed off that Little Witch Academia got any game content and KLK didn't. Even if she isn't in a video game, I'll still vote for her.) I would have said Kat from Gravity Rush, but nintendo switch version killed her chances completely.
But the way I see it, they'll probably focus on games they've most likely published or made.
I can see this game having Hokuto no Ken, Skullgirls, Arcana Heart, etc characters. (If they can get the rights to them obviously).