Saw the other Mewtwo Mega evo. The one that wasn't revealed in the beginning. I'm guessing X? At any rate, it certainly looks like the better one of the two, and a more natural jump. Then again, the original Mega evo looks like what mankind would've got if they kept Mewtwo in the labs for longer than expected.
Eh, either way, I couldn't help but laugh at trailers with a little girl trainer commanding Mewtwo. I'm gonna have to do better to suspend my disbelief for this game, hah. That or Mewtwo's gone really soft over the past decade plus.