Here comes a whole bunch of Star Tracker transformation pics. His crossdressing cosplay sees him trying to find all sorts of little odds and ends he can use in his outfits, and more than a few times he's gotten his hooves on a cursed item that transforms him :D

When a goo pony dies their core will be left behind. Over thousands of years it can crystalize, but be very careful not to touch it or you'll turn into a goo pony in an instant :P

And the rest:
Regular form
Harpy form
Inflatable form
Skunk form
Lamia form
Portrageist form
Siren form
Goo pony form
Twilight Sparkle form
Zebra form
BONUS: LIVING DRESS
BONUS: SHADOWBOLT