Mega Metagross confirmed.
•Mega Sceptile (Grass/Dragon) with LightingingRod (How is that useful?).
•Mega Swampert (Water/Ground) with Swift Swim (Now bulky and fast)
•Mega Diancie (Rock/Fairy), ability unknown
•"Mega" Groudon and Kyogre known as Primal/Prehistoric form. (Perhaps more like Mega Deevolution)
•Brandan is more tan and loses his pants from Emerald (compare his Emerald art with ORAS). May is now blonde and is wearing a bow instead of a bandana. Possible character customization.
•Steven's got a Mega Charizard X. (Run!) Also, he's looking for Mega Stones. (Because he likes getting stone(s) and wants to know how Mega Evolve works)
•Team Magma and Aqua redesigns.
•Your Mega Ring from X and Y is now a Mega Bangle.
Primal Groudon is Fire/Ground. Which means Kyogre will kick Groudon's butt twice as hard now. Unless Game Freak has something in plan for Groudon.