It'd be a travesty if I didn't post in this thread, so even though I haven't had the time to test all these Mew sets being discussed, I thought I might offer my opinion on what is being researched and propose a set or two as well. Here's my list of every Mew set that has been discussed thus far, with my comments on how viable I think each one is:
Baton Pass - Known. Thumbs Up
Lead - Known. Thumbs Up
Transform - Known, I can't personally attest to its effectiveness but I can see it being viable and it's already on-site. Thumbs Up
Double Status - Known, again I can see it being viable even though I wouldn't really ever use it. Thumbs Up
Anti-Lead - Honestly I don't see what this set does that my Lead set doesn't do. If you want a Psychic-type anti-lead use Deoxys-A instead. Thumbs Down
Swords Dance - Several people have posted different versions of this set, but IMO the best is this: Swords Dance/Low Kick/Sucker Punch/Explosion @ Life Orb Thumbs Up
Support - Mew just doesn't have the bulk to pull this off like Blissey and friends. It has better things it should be doing. Thumbs Down
Block - You would have to build the whole team around this concept, but it's unique and I can certainly see it working effectively. I would like to see more discussion of this set and a pseudo-Baton Pass team that could be centered around it. Thumbs Up
Nasty Plot - Again, there have been several ideas tossed around, but I think that the best option is this: Nasty Plot/Aura Sphere/Ice Beam/Thunder @ Lum Berry. EDIT: After further thought I don't think this set lures and weakens/KOs CM Mewtwo switchins as well as some of the other sets (like Choice Band or Swords Dance), so I'm changing my opinion to Thumbs Down
Super Fang - on a defensive sandstorm/hail team, I think this set could be devastating if used well. Tyranitar especially would do wonders for this set because it can take out the hated Giratina. Thumbs Up
Mixed Attacker - I would always use Deoxys-A or Mewtwo instead of this. Thumbs Down
Physically/Specially Defensive aka "Nibbler" - Sorry Jibaku but I just think Mewtwo does the stalling thing better. I'd rather use the Super Fang or Double Status sets over this. Thumbs Down
Bulk Up - Again, Mewtwo does this better. Thumbs Down
Now I have two sets of my own to put forth for discussion:
1. CBMew
Item: Choice Band
Nature: Jolly
EVs: 252 Spe/252 Atk/6 HP (Not sure if there is a better option, I may run some calcs to see if I can sacrifice some Atk in favor of HP to capitalize on Mew's bulk)
Moves: Explosion, Ice Punch, Low Kick, U-turn
This set is pretty straightforward. U-turn and Explosion are GREAT moves to have on a Choice Bander, and Low Kick + Ice Punch has amazing coverage in Ubers. If people want calcs to show CBMew's effectiveness, I can work out the best EV spread to use and post them here.
2. Trick Room Lead
Item: Lum Berry
Nature: TBD (probably Brave or Quiet)
EVs: TBD (A mix of power and bulk)
IVs: TBD (depends on the nature, obviously you want as little Spe as possible)
Moves: Explosion, Flamethrower/Overheat, Trick Room, U-turn
I have used this set before as a lead for a Trick Room team and it performed excellently. (It isn't very good outside of the lead spot.) Against most leads you just Trick Room and then U-turn or Explode. Against Deoxys-S, instead of the Taunt/U-turn mindgame you play with the normal Lead set, your choice is between Trick Room and U-turn. The fire move roasts Forretress who is a massive pain for Trick Room teams to face. I haven't decided yet whether Flamethrower or Overheat is the better option - Overheat OHKOs all Forretress without any SpAtk investment but misses 10% of the time and drops your SpAtk 2 stages, whereas you need 184 EVs and a Quiet nature for Flamethrower to always OHKO Forretress.
EDIT: Has anyone tried using a defense-boost passing Mew (something like Me First/Iron Defense/Amnesia/Baton Pass) on a dedicated Baton Pass team that can use other Pok émon to pass speed and offensive boosts? It's worth a test at least.
Any feedback, positive or negative, would be great - this is a research & discussion thread, after all. I tried to be as objective as possible in analyzing each set, but obviously there will be people who disagree with me. Also if I missed a set please let me know.