Some Aasimon don’t have a specific plane of origin and can be found on any Higher Plane. Those include:
Asura – They are aggressive and arrogant, have green skin, four arms and two leathery wings. They are archenemies of the Rakshasa.
Monadic Deva – They are purple-skinned, have two wings and a single eye. They are stoic watchers that often refuse to interfere.
Planetar – human-like, with four wings and no kind of hair.
Solar – human-like, but huge. They have hair but no body hair and have eight wings.
A note on higher-planar creatures
While Fiends are quite varied and have a multitude of forms, most Aasimon were ridiculously generic and looked pretty much the same. They looked like strong and pretty humans or elves, with minor mammalian or birdlike features (especially angel wings). Per, Asuras, Devas, Archon, Devas… so I decided I had to partially reinvent them.
I decided to make it so that Guardinals had animal features as normal; Eladrin are all elf-like but with shapeshifting powers; inhabitants of Celestia are called Celestials rather than Archons (let’s use the 4E definition of Archons – elemental warriors). Celestials are humanoids attuned to specific objects and I have changed their appearance a bit to make them less like the other “angelic” beings (asura, deva, planetar, solar).