Luigi player
Smash Master
Wow, wow, wow... wait a minute. What did you just say? Mewtwo's not a good fighter? Do you even play Pokemon games? No need to take up roster space? I'm sorry to tell you, but Mewtwo's probably the best to represent the Pokemon franchise. Assist Trophy.. oh god, no.Not only do I think of Mewtwo's replacement as possible, but I also think of it as beneficial. I happen to like Mewtwo, but he's just not a good fighter, whereas Lucario definitely would be. Make him an assist trophy and move on. There's no need to take up that roster space when only a miniscule amount of people actually like using the character.
And let me tell you this: Mewtwo's only used by a few people, because he just sucks in Melee. He's the worst on the tier list. What if he'd be on the top? Very very many people would use him. Like Fox, Falco, Marth... it all depends on how good the character is, because people want a higher chance to win.
You can't just take Mewtwo out and replace him by a stupid new Pokemon, that's not even strong. Just because of a movie? Well, Mewtwo had even more than one movie where he was the main Pokemon. He's just badass with cool psychic powers, and is one of the strongest Pokemon in existance.