Discord

Discord is the enermy of Thomas and Twilight Sparkle. Discord will make his first appearence in Thomas and Twilight Sparkle Goes to FernGully: The Last Rainforest where he joined forces with Diesel 10, Queen Chrysalis and Hexxus to get his revenge on Twilight and her friends for turning him back into stone after he cause choas in Ponyville.

He also in the Bowser side in Super Mario and Friends new Adventure.

Trivia

 * Discord will become Pooh's enemy until after reformed by Fluttershy in the future.
 * Discord will become the FT Squad's enemy in The FT Squad's Adventures in My Little Pony: Friendship is Magic, but will later become an ally after getting reformed by Fluttershy.