My Little Pony: Equestria Girls

My Little Pony Equestria Girls is an animated feature film starring characters resembling the main cast of My Little Pony 'Friendship is Magic' as teenage girls.
Princess Twilight Sparkle's crown, which is the element of magic, is stolen by Sunset Shimmer who disappears into a mirror that leads into the human world. Without the crown, all the other Elements of Harmony will have no power to protect Equestria, so Twilight and Spike go through the mirror to chase after the culprit to retrieve her crown.
They discover themselves in a new world where Twilight is a teenage girl and Spike is a talking dog, and find friends that resemble their pony friends from Equestria. Twilight works with her friends to become Princess of the Fall Formal to win her crown back from the human Sunset Shimmer and to 'change the destiny of these two parallel worlds'.