There should actually be 3 locked characters (4 total with Emma present, if you have not gone through the game). Deadpool, Ironman, and Professor X. For some reason, the new character is a locked character, with no way to unlock it except for the... unlock all characters cheat! (I completely forgot about the locked character nonsense.) The cheat is: Right, Left, Left, Right, Up, Up, Up, Start (best done with a game pad). If there is some other way to make her show up as unlocked without using the cheat, I'm sure BliZZ or Noel might know, though I asked already, and was told the same thing as I am telling you now.