John Stewart and Hal Jordan have the same powers though. They both were known as "Green Lantern" for a time. It makes since for them to be alternates. The alternates in Injustice are different interpretations of the same base character. Man of Steel Superman is not the same character Red Son Superman, because they are from different canons, but they are different interpretations of the same character. Lucas, Roy, Falco, and Wolf do not have the same abilities as Ness, Marth, and Fox, nor are they the same character by any means. They just have similar looking moves. (significantly less so in Wolf's case) Lucas's personality does not fit Ness's animations, Marth doesn't have fire, or Roy's cool winning poses, Falco and Wolf don't fit Fox's personality. AND THE CHARACTERS WOULDN'T PLAY THE SAME. It appeals only to the lowest common denominator, while pissing on the people who enjoyed playing as the characters to begin with. Do you think Luigi should be a Mario alternate?
I'm sorry if I sound so angry here, it's just this topic really pisses me off. "Alternate Costumes" should only be the same character in a different outfit. That is basically what John Stewart is in a way. He is his own character, sure, but for a while, he was the main Green Lantern in the Green Lantern comics. Stewart and Jordan have the same powers too. Just swap out the voices and it works. For other characters who have no relation other than similar animations, it does not.