Japanese magazine Corocoro just revealed new mega evolutions for the upcoming games Pokémon Omega Ruby & Alpha Sapphire.
Groudon and Kyogre also have new forms in the game allowing them to transform into Prehistoric/Primal/Primeval forms. Although whether or not these forms work the same way as Mega evolution has not yet been revealed.
Ability: Lightning Rod
Ability: Swift Swim
Ability: Not revealed