Unfortunately, the Pegasus is a Crowns only pet - it's impossible to put them into the hatch-maker kiosk at this time. Aside from hatching, you can also get this pet from the Immortal's Lore and Wysterian Lore card packs.
I think I might have a pure one on my Death wizard that's trained to adult. I was trying to hatch it with a Yuletide in order to get a Harmonious Sprite. Yeah, that didn't work.
Anyway, Fallon has a pure adult Pegaus if you just want to hatch for the body type.
The wizard is Fallon Raven, a level 92 Death. I'll be available to meet in-game this during the mornings this weekend if you'd like. I'm usually in Phoenix realm and I live in the Pacific time zone. On weekdays, it's easier for me to meet in late afternoons (4pm through about 6pm Pacific time).
If someone else has a better Pegasus pet for you, then go with that. Let me know if you want to meet!
Alia Misthaven