Now here is my idea.

Ifrit: Aithon - would have bright red wings, like a phoenix? and a trail of fire!

Garuda: Xanthos - would have a green and white feather trail like its weps, and feet, right, and a trail of feathers flowing etc!

Titan: Gullfaxi - idk... its a rock pony, i guess rocks flowing and brown wings, but its kind of idk, its a rock pony.

Leviathin: Enbarr - Blue wings with water trailing off the back tips, but not the front, so it looks like water is flowing off, that or bubble wings, bright blue bubble with water in the middle, with sharp bubbly edges? Im not sure.

Rammuh - Markab - LIGHTNING WINGS PLEASE - no further description needed

Shiva - Boreas - bright white wings, with blue tips and ice trailing off the back, would be beautiful and match the main etc