Sylveon doesn't really share anything with Skyla though. That was a rushed conclusion brought up with very little actual support. The colors aren't right and Skyla's hair pin/bow is a flower, not a butterfly. The colors are closer to Iris' champion dress which has a pale ribbon in the back and a bow on the front.
Also the "wing" is the same shape as Burgh's badge not Skyla's.
Its closer to Insect than Jet.
I think the shapes on the egg are just coincidence as the ones behind the ear we'll never be able to make out. If the top part isn't two separate images like I think then it looks like a claw/tooth.