Polychromos and black ink.
My little Pony/Rarity (c) Hasbro Inc. and Lauren Faust
art (c) me
(Note by uploader, who isn’t artist: this dress was part of the G1 “Pony Wear” toyline, where they sold separate clothes and accessories that would fit any regular-size pony. This particular ensemble was called “Hearts and Candy” or “My Valentine,” depending on what country you’re in. It’s got cute li’l red shoes, too!)