Xerneas #716 - Yveltal #717 - Zygarde #718
"Yveltal is based on the Hawk Veðrfölnir or the unnamed eagle. According to the Poetic Edda, the unnamed eagle resided at the top of the world tree Yggdrasil."
"Xerneas’s appearance is based on the four stags Dáinn, Dvalinn, Duneyrr and Duraþrór. According to the Poetic Edda, the four stags resided in the trunk of the World Tree Yggdrasill and ate its branches and fresh shoots."
"Zygarde is based on the Níðhöggr. Níðhöggr is the the serpent from the Poetic Edda which resided at the bottom of the world tree Yggdrasill and gnawed at its roots."