Wow, this tier is beyond awesome. There should be list of sets that people post in the OP though, this is getting hard to surf because of its length. Wondering if Mewtwo with the following set is viable:
Mewtwo @ Life Orb/Leftovers/Lum Berry (dunno which)
Timid Nature (+Spe, -Atk)
- Psycho Boost
- Draco Meteor
Substitute upon the switch to the counter, and then act accordingly. After 3 attacks, you're at +6, at which point you 2HKO Blissey (+Sdef nature) with everything, dealing a minimum of 56.3 with Overheat/Draco Meteor and a minimum of 84.45 with Psycho Boost. I'm concerned with it being outsped by pranksters but it seems like it could smash heads if used correctly. V-Create could be used in place of Overheat with a -Sdef nature to boost speed, but it's pathetically weak without boosts. Sorry if this post sounds noobish but I'm new to this sort of thinking.
Oh yeah, and Lum Slaking posing and Shedninja FTW.