A pony with magic and wings.

Twilight Sparkle is the first Alicorns that was not born as one.

Alicorns have built-in seatbelts.

Fully grown Alicorns all have visible hooves.

All Alicorns are immortal.

Changelings are Unicorns/Alicorns which are taken over by the Changeling-parasite. This parasite lives on Magic and uses the dead bodies to convert friendship/love to Magic. The wings are part of the parasite.