I've recently been playing on a competitive battle simulator, Pokemon Showdown. I've made a lot of teams in which didn't completely fail. Because of X and Y, a new threat was added into the metagame: Mega Evolution. Now there's huge threats such as Mega Mawile, Mega Scizor, Mega Gardevoir and more. I think everyone knows that some just completely suck **Blastoise**, but many are powerful, and fun to use. Already, Smogon has banned three of them to Ubers; Blaziken, Lucario, and Kangashkan.
So the main point of this is just what sets have you had the best luck with? I know Mega Venusaur's been pretty popular for a staller, and Mega Charizard Y's been the sweeper every other team has. What's your favorite set to run on any Mega Pokemon?