Quote Originally Posted by ElHeggunte View Post
All of the primal mounts are supposed to be flight-capable at some point.
Since we have the fart powered adamantois, I think it's only fair that Slephnir and Fenrir fly as well. Slephnir could fly in Mythology and Fenrir has flown/levitated in previous final fantasy games.

So in the wake of Adamantois the Fart Powered Gamera there should be no limits to changing ground mounts to flying.