Didn't Mewtwo get a sizable makeover in the X/Y gen what with the Mega Evolutions and the female persona?
But then since Lucario has Mega Evolutions, wouldn't that mean he would be with the X/Y group? And Mega Charizard?
...Yeah, I'm done with this, I'm beginning to confuse myself with my own semantics.![]()
Mewtwo's primary form changed about as much as Charizard though (which is to say not very much at all). The female voice was exclusive to the movie and was a different Mewtwo than the one that originally appeared in the anime, not necessarily a retcon or anything.