Here's two possibilities for Mewtwo that buck the usual trends:
Mewtwo @ Leftovers
Hasty/Naive
Pressure
- Psychic/Ice Beam
- Thunderbolt
- Calm Mind
- Brick Break/Shadow Ball
Mixed Mewtwo of sorts - a lot of people forget that Mewtwo has a Base 110 Attack stat, which is a very impressive number to have. You can either go Psychic/Thunderbolt for STAB, or use Ice Beam/Thunderbolt to get extra coverage but no STAB. Calm Mind will boost your Sp.Attack and Sp.Defense nicely, and the physical move depends on your opponents - if you'll be fighting other ubers, go with Shadow Ball since a lot of ubers are weak to it, but if you'll be facing the non-uber Special Walls, Brick Break will serve you better.
Mewtwo @ Leftovers
Bold/Relaxed
Pressure
- Ice Beam
- Recover
- Taunt
- Calm Mind
Defensive Mewtwo. This is a tricky one to deal with, since not many people will expect Mewtwo to take a defensive role, even though it does have the stats to do it. Ice Beam since nothing is immune to it and quite a few ubers are weak to it, Recover to...recover your health, Taunt to tie down the opponent and force them to only use attacking moves on you, and Calm Mind again boosts your Sp.Attack and Sp.Defense stats. This can really tie an opponent in knots if you know what you're doing.