Disclaimer:
Gusteon belong to Queen Wisp and Hurricane. If you would like to make a Gusteon(I don't see why though) please ask.
Overall, Gusteon is very small Pokemon, as well as unique. No one Gusteon looks the same. One might have spots on their ears, others may just have spots on their tails. They're the only Eeveelution capable of flight, and the lightest. If a Gusteon is a hybrid between a Gusteon and a Eeveelution from lower ground, it will have small wings and wont be able to fly, or it's wings will look much more different than a common Gusteon. It is more likely a hybrid Gusteon will have small/long wings than any other mutation.
Appearance[]
Gusteon is sky blue, and is covered in white spots. The blue can sometimes vary in shades, but the white will remain white. Their spots can vary in size, but are almost always round.
they are much lighter than the other eeveelutions, and have hollow bones in order to fly.
Sometimes their wings move according to their emotions. I'll just give you a quick guide because i have nothing better to do.
Medium = Normal position
Calm, sad = Drooping
Angry = Slightly forward, tips facing upward.
Happy = Slightly raised
Evolution[]
Eevee evolves into Gusteon when falling from a high place, such as a mountain, or cliff. Basically, just chuck an Eevee with Gusteon genes off a cliff and it's a Gusteon.