Okay, I don't know where to post this so I'll just say it here.
The OU Stallbreaker Mew set needs some adjustments, mainly minor ones. First of all, it should always run Timid 88 Spe, this way it will outspeed all variants of Gliscor except 252 Spe, all variants of Lando-T, and anything below that. It should also run 36 SAtk so it can successfully OHKO Lando-T. I've been put in some pretty bad situations early-game where I don't have stealth rocks up and Ice Beam leaves Lando-T at less than 10% HP. This isn't good. 36 SAtk ensures a safe OHKO, and with the Spe evs Mew has LandoT will never outspeed except if it's scarfed. Also, Psychic should be mentioned in AC and not slashed over Ice Beam. Ice Beam is the bane of the set I'd argue, really.
So the set I'm seeing should be changed into is this:
name: Stallbreaker
move 1: Will-O-Wisp
move 2: Taunt
move 3: Softboiled
move 4: Ice Beam
item: Leftovers
nature: Timid
evs: 220 HP / 164 Def / 36 SpA / 88 Spe
It still keeps the necessary bulk to tank whatever it could with it's previous EV spread and now it can also still effectively check Dragonite, Garchomp, Lando-T, Gliscor, and the likes.