Played against quite a bit more mewtwos lately. Several good ones on anther's and one good one several times in live tourney. I think it's something like +1 in Mewtwo's favor. But only because of waft. Miss waft and it's more like +2 in Mewtwo's favor. His buffs are real. Mewtwo has strong aerials, nair and fair are godly. Mewtwo has a much better neutral. We lose pretty hard on the ground and in the air. Mewtwo can play passively and carefully and space Wario out with Shadow balls and aerials. Approaching is really tough. Wario really can't take advantage of edgeguarding either. Even with bike, mewtwo can just jump into it and use his reflector which really negates Wario's normal bike edgeguarding tactics. Throwing bike at him is pretty useless. Mewtwo's up B makes him hard to edgeguard in general. Mewtwo/Wario are about the same in terms of mobility, but Mewtwo has a strong range advantage.
The only thing Wario really has going for him is Mewtwo being vulnerable to waft. His size and floatiness help make weak fair to waft easier to land especially I've noticed. And his weight means he dies at 30% or so center stage with rage.
EDIT:
After getting more experience lately and studying the MU more, I have to revise and push this one to more like +2 in Mewtwo's favor, or 60:40. Mewtwo just keeps Wario out really well and I feel you're mostly forced to approach because of shadow ball. Can you outcamp him? I don't see it but I'd love to hear more opinions on that.
Mewtwo wins neutral by quite a lot. The range disadvantage hurts really badly. His aerials are kind of free on Wario, wario can't challenge mewtwo at all in the air. His nair just auto wins over every one of wario's moves it feels like and mewtwo can kill wario pretty early. His fair is ridiculously strong and his upthrow killthrow is braindead good. Get grabbed at 120 or so and you're dead for sure off the top no matter where you are on stage. If you get grabbed on platforms or if mewtwo has high rage you can die even earlier.
I'm not even convinced wario wins offstage. Seems pretty even. Shadowball can knock you off bike and mewtwo's drag down nair shenanigans offstage needs to be watched out for. And we really can't edgeguard him. Like I said before bike edguarding is mostly negated by mewtwo's ability to use reflector when coming back to stage. About all you can do is try and place a lingering dair just off the lip of the stage to try and catch the 2 frame. Or try and catch the high recovery with an aerial. But mewtwo is really really hard to gimp in my experience. The teleport recovery really makes it difficult.
I feel like it's one of those MU where wario gets outcamped but at the same time can't approach. I really don't see what Wario can do against mewtwo. Mewtwo has so many options to kill wario and keep him out, whereas wario struggles to get in, finish stocks or challenge mewtwo anywhere. You kinda have to hope they mess up their spacing so wario can have a chance to get in and land a waft. It's looking pretty bad from my end. I'm thinking it could potentially be Wario's 2nd worst MU behind Cloud. I would love to hear opinions from high level warios, I'm only a mid level wario so these opinions just reflect my experiences at my level of play.