User blog comment:Zeref Fullbuster/Gym Leaders, Champions, Frontier Brains and Legendary Pokemon/@comment-4980287-20151125125422/@comment-5301469-20151125130518

Possible but from what I read, the Zygarde in Terminus Cave fled. It's possible that it is Z-2 but the intro of XY&Z has the one from Terminus on Flare's side. I think that if Z-2 could form with Squishy, they could create the Perfect forme (after all, Perfect forme has Red and Blue on each side of its body).