Hey, so why cant characters from the franchises present in the game just be on the roster despite not being in Death Battle?

Like, seriously, I'd like to try out Sakura or Falco Lambardi sometime, but they're not in the game, despite their friends being in the game..... Or more ridiculously, Yusuke, who isn't in the game despite Freakin' Hiei being here.

What is all this about? Could they only get the rights to ONLY the characters who were on the show, and not just the franchises in general? Luffy needs to be in the game, even moreso than he needs to be in Death Battle itself, tbh.