>>55918420After thinking for a bit I think that Xerneas and Yveltal are Zygarde's right-hand men, rather than Zygarde being their tard wrangler like Rayquaza. Neither of them seemed out of line in X&Y or anywhere else in Pokemon's lore, infact they seemed quite chill when they met the protagonist.
I believe that Zygarde calls on them to do their jobs i.e. calling on Xerneas to revive ecosystems and calling on Yveltal to prevent overpopulation or kill off invasive species, hence the blue and red snakes on its body.
