Where would he be in power compared to the rest of them? And yeah in the comics Superman is practically a god and if he goes to the center of the sun can get stupid powerful, assuming if he does that Mewtwo can up his spc attack at the same time. --- Mod this. http://www.huffingtonpost.com/2013/06/06/nsa-prism-data-mining_n_3399310.html
Why would he join them? He'd be better on the Avengers.
I think it'd be fair, especially with superman. Hawk girl is an embarrassment though.. I'd say yeah behind superman and batman. He's not as nice as Superman obviously, if anyone saw that one fight between Superman and batman, even though batman won, Superman totally could have laser eyed him any time he wanted. --- Mod this. http://www.huffingtonpost.com/2013/06/06/nsa-prism-data-mining_n_3399310.html
With team members ranging from Batman (who is physically about the same as any non-superpowered characters but still above "normal" humans due to his training), the Hawkpeople (who are more or less more durable and stronger humans with wings), and Martian Manhunter (basically Superman with a few extra powers and a fire weakness) being part of the League, I would imagine Mewtwo would do just fine.