PrinceOfFacade
Ghost-Type Master
I just hope Zygarde isn't tied into the main story, that thing had it's chance and there is no reason for it to hog spotlight that Solgaleo and the other legends rightfully deserve.
I'm actually hoping it is.
It will piece together the missing link in X & Y. Besides, it has already been confirmed that Lillie will play an important role in the game's story, and she clearly has a Zygarde Core in her bag. Not to mention we will be tasked to find Zygarde Cells throughout Alola. I'm guessing Sycamore sent Dexio, Sina, and Lillie to summon Zygarde. Lillie keeps hold of the Core and hides among Professor Kukui, while Dexio and Sina find a way to collect Cells