Let me just say: I am so guilty of underestimating Mewtwo. Yesterday, I was mostly just frustrated by his lack of defense. But today, I really started to appreciate his offensive options and mindgame potential. At this point, I'm very unsure of where Mewtwo will be.
Basically, it seems to me that Mewtwo has a very very good advantaged state, but a very bad disadvantaged state (unless teleport is actually fast enough to safely escape combos. I can't tell yet). I think mewtwo is going to be extremely hard to use and harder to master, but his potential for early kills is ridiculous. I'm feeling much more confident in him now.
A few cool things I've noticed/pulled off
Fast falling nair on an aerial opponent can combo directly into usmash for a kill
Shadowball is extremely useful. The uncharged ones are slow enough that you can try to get a grab out of shieldstun. The charged one does incredible shield damage, so some people try to jump over it. Easy usmash.
Dthrow and confusion, while not guaranteed, can seriously throw the opponent off, and are relatively easily to capitalize on if you can read your opponent.
Uair is useful once you get used to the timing and deceptive range. Rising uair combos well into things.
Rising dair is awesome. Both the upwards and downwards hitboxes are great against a character trying to recover high.
From the ledge, stand up disable is such a great mixup. If your opponent isn't expecting it, free smash or throw, and it's so incredibly satisfying.
Dsmash reminds me of MK's fsmash in that it's practically impossible to punish if spaced well.
Jab to grab is so great, as is jab to disable.
His airdodge is so great, I would argue one of the best in the game. You can short hop airdodge to fair, and it's hard to know where he'll end up.
I could go on and on about cool little things he can do. I'm really enjoying his tricky playstyle.
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