I remember watching the My Little Pony Movie when I was about eight years old, maybe ten. I had three younger sisters and we got the movie to appease them one evening, with cute cartoon ponies.
Imagine our surprise when some of the ponies were kidnapped by one of the coolest bad guys I remember from my childhood. A giant centaur (but not a horse-centaur, a bull-centaur) and he was more a minotaur than a man. He drove a chariot pulled by dragons and stole the ponies to turn them into these mindless vicious beasts.
The ponies had to go on a quest, meeting up with a funny little satyr/leprechaun guy and a small friendly pink dragonet.
Eventually they broke into the masive castle, which IIRC had a name like the Castle of Neverending Darkness or something similarly melodramatic. Here they freed some of the ponies who had yet to be turned into dragons and fought the bad guy.
His plan turned out to be unleashing the darkness he carried in a pouch around his neck and creating "The Night That Never Ends!" But the plucky dragonet got the pouch and destroyed the bad guy, transforming everything back into their original forms.
My Little Ponies may have been cutesy little girls toys but that movie was one of the more fun movies I saw when I was young.
I could find no information for this movie on www.imdb.com. On that website I find the only My Little Pony The Movie involves a witch who tries to cover the land in purple ooze. Was I dreaming?