By 
Japan’s CoroCoro magazine has revealed more Mega Evolved Pokémon that will be present in Pokémon Omega Ruby and Pokémon Alpha Sapphire. (Thanks, Serebii.net and @chisa_suiran)
One of these Pokémon is Mega Altaria, who is a Dragon/Fairy-type with the Pixilate ability. Another is Mega Lopunny (Normal/Fighting-type) with Scrappy. Finally, you have Mega Salamence with the Aerilate ability.
Also available in the game is a Shiny Beldum, which comes holding its Mega Evolution stone. It looks like Steven won’t be the only one with a Mega Metagross.
Contests have been elaborated upon a little as well. A character in the game named Lucia gives you special clothes for participating in Pokémon Contests.
CoroCoro also reveals that the cosplaying Pikachu in the game get special moves depending on which outfit you dress them up in for Contests. Pikachu Rock Star gets Meteor Smash, Pikachu Ph.D. gets Electric Terrain, Pikachu Pop Star gets Draining Kiss, Pikachu Belle gets Icicle Crash, and finally, Pikachu Libre gets Flying Press.
