I don't want to be disrespectful now, but for God's sake, STOP ASKING TO BAN THINGS! lol
Seriously guys, this metagame serves to a purpose, the purpose of being as versatile as it can with a few exceptions, and those exceptions are things that overcentralize the metagame.
Basically this metagame is Pure Hackmons (that allows EVERYTHING, so bans shouldn't be happening), but it restricts ONLY the broken top-tier things.
There are people here that wants to restrict mega forms to their megastones and/or only one mega form per team, but the only unique things on this metagame are Stats + Type, and if you guys look to most mega forms they don't even have unique type and their total stats are not even Uber-like. Really you want this banned?
What about banning Dark Void because it is luck-based? Let's ban Hydro Pump then, because Surf exists lol
I mean, Spore gen 5 was better, but it wasn't centralizing the game (well, it was, but not in a broken way) and it wasn't banned. Now Dark Void should be banned because it can MISS? It has absolute no sense at all, if you're affraid of missing attacks pick only the 100% accuracy ones, because the fact it can miss only makes it more far away from be banned, since this makes it less overpower.
About Mewtwo-X and Y, they're really strong, but they're not unstopable forces of the universe, guys lol
Everything will depend of what set they're using. Wants to stop Contrary? Unaware Cresselia. Wants to stop Mold Breaker Sweepers? Prankster Topsy-Turvy. Wants to stop Poison Heal? Probably Magic Bounce Cresselia or Lugia with Gastro Acid are good options. And so on.