When visiting the Crystal Empire, Twilight's Crown is stolen by Sunset Shimmer, Celestia's former student, & adopted daughter. She leaves into a magic mirror that teleports anyone into a parallel world. A Human World. That only opens every 2 1/2 years for one week.
Twilight & Spike leave for this world & become a human girl & a dog. They only have 3 days before the portals closes. They find Canterlot High School where Sunset rules as the Bully. Twilight soon meets her friends' human counterparts. They try to convince the school to have Twilight win the Fall Formal so she can get the crown & return home. Sunset Shimmer tries to foil their plans. Eventually Twilight confesses who she is to her friends and they help her prepare for the Formal. Twilight wins the crown & stops Sunset from destroying the portal. She gets the crown & becomes Demon Sunset. Twilight & her friends find the Magic of Friendship & defeat Sunset. But Sunset has too much of the Crown's power, so Twilight takes her to Equestria & has her make amends with Celestia. Twilight returns to Earth where she has the Humane 6 help her be a better friend. Twilight leaves for Equestria & takes the Magic with her.
Mid-Credit Scene shows G.I. Joe getting news on what happened at Canterlot High.
The Movie shows Sunset Shimmer's past on Equestria. The framing device would have Pinkie & Rainbow Dash pausing & having their own MST3K commentary during the movie. Also an animated/live action hybrid.
