I think it would a really good idea if they took the assist mechanic from Marvel vs Capcom 1. In that game you would pick a character that was dedicated to assists only. There was also a finite number of times you could use them in a match. I think Injustice should adopt this mechanic but change it a little. Maybe make it cost meter for a guy to come out, or make it have a refresh rate. Maybe some characters cost less meter or refresh faster.

I think this would add more depth and fun to the game, but it could also include more minor and obscure characters without taking anybody else's place on the roster. I was think characters like Daxtar the red lantern cat or Azrael. Characters that are either obscure or would just be weird playing as them in the actual game. I would also like to see characters varying from small to large.

My personal picks would be Daxtar, Azrael, Mera, Killer Croc.