Kyogre and Groudon's new "formes" are named Primal / Primeval / Prehistoric. Their "formes" are a regression called "Ancient Devolution," perhaps their original formes before they fought?
Mega Sceptile is Grass/Dragon and has Lightning Rod.
Mega Swampert is still Water/Ground and its Ability is Swift Swim.
Mega Diancie is still Fairy/Rock and its ability is unknown.
Like the originals, Team Aqua and Magma return depending on which version you are playing. Team Magma is again headed by Maxie; his admins are Tabitha and Courtney. Team Aqua is lead by Archie; his admins are Matt and Shelley. All of them feature new designs or are redesigned.
Steven Stone returns with a Mega Charizard X. He is researching Mega Evolution.
The Mach Bike and Acro Bike are in the games again.
The Mega Evolution item is called the "Mega Bangle" and is used by Brendan and May.