Yeah. A dark flavor for this deck would be pretty good since Yveltal can accelerate to Mewtwo.
That's definitely true. If Mewtwo becomes popular that'll be one way to keep it in check.
I disagree. Crobat adds another level of damage to the deck that it really misses out on otherwise. I don't think Golbat is gonna be enough to be competitive, but we'll see. And yeah, Sceptile gives Mewtwo a hard time.
Sure. What I meant was that healing 60 damage can save you from getting 2HKOed. Instead, you would be able to survive the second hit and retaliate with Damage Change.
In terms of techs there's nothing I can think of off the top of my head. Ideally, you would want a Psychic-type who can potentially hit for big damage for low amounts of Energy.
Meloetta LTR actually fits this bill perfectly: If Mega Mewtwo has five Energy on him, Psychic is a OHKO (220 damage). Unfortunately it's not legal for Standard and there is no substitute for it. Mega Mewtwo thrives on Energy, so decks with low Energy costs will do well against it.
Thanks for commenting, everyone! Keep them coming.