>>14256995Actually Mega Charizard Y is probably one of the better mega forms revealed right now. Drought via Mega Evolution has weird priority. He's faster than anything else that can set up weather, yet he sets it up last thanks to Mega Evolving. So he overwrites Sandstream and Drizzle immediately. Then he has the speed to get a first attack off, giving him aggressive momentum with a solarbeam or focus blast. Still sneaky stones to worry about later into the match or rock moves in general, but just put a good spinner on the team and play smart, you should be fine.
The other two better Megas right now are Blaziken and Lucario.