>>19771272Xerneas is closer related to Celtic myths, where deers was called "fairy cattle", and the god of the forest and all animals was Cernunnos, who had antlers.
Birds have generally been associated with death and destruction in Europe, so Yveltal could be based on all sorts of things.
Zygarde is based on Lou Carcolh, a giant dragon that was part snake and part snail, and had many tentacles.