I'm currently Beta testing the next Pokemon Game called Pokemon XZ and Pokemon YZ. Please understand that I can only share some Information and can't go too much into detail so nobody can figure out where the Leak comes from.

-Pokemon XZ/YZ are sequeles to X/Y.
-Not only new Story but also new Pokemon and new Region.
-About 70 New Pokemon
-One of the New Pokemon is a Dragon Eeveelution as counterpart to Sylveon.
-New Region is based on Germany it's the Region with that Kalos was in War 3000 years before.
-Just like Germany and France the two Regions were hateful enemies in the past and best friends in the present day.
-Chespin, Fennekin and Froakie return as Starters.
-New Mega Pokemon including the 6. Gen. Starters
-You Recieve the Zygarde Core early in the Game. (Blue One in XZ, and Red One in YZ)
-While you progress trough the Story Zygarde will evolve in different forms until it's reaching 100%.
-Blue and Red Core have different forms. The 10% and 50% Zygarde you know are the evolutions of Red Core Zygarde. The Zygarde forms in XZ will look diffrent.
-Besides 10, 50 and 100% are: 25% and 75%
-At Games Climax you will receive either the Red- (XZ) or the Blue Core (YZ) to activate the 100% Zygarde
-After Elite Four you can visit Kalos (starting from Couriway Town)
-After Kalos Elite Four you can visit the Hoenn Battle Frontier.
-scheduled Release: June 2016 (worldwide)