Fey and Aberrations are different types. Some people have argued for avangions being fey. Some for outsider.
Have a look at the creature types here. What we are looking for are what you might call “ascended types”. So fey, outsider, aberration, dragon, elemental seem to be what we need.
I’d probably make the shadow shifter an [outsider] with the [native] subtype, assuming there is a connection to the Black - I am not that familiar with it. As for the avangion, I am easy going. I am OK with dragon, aberration, fey or outsider. I think there is a case for all of them.
Hah! It gives me an opportunity to pontificate.