Little Bear's Adventures of My Little Pony: Equestria Girls - Rainbow Rocks

Little Bear's Adventures of My Little Pony: Equestria Girls - Rainbow Rocks is another upcoming Little Bear/MLP:FIM crossover to be made by Hiatt Grey.

Plot
Former Canterlot High School bully Sunset Shimmer, who has reformed after being defeated by the magic of Twilight Sparkle's crown, is ostracized by most of the school despite her efforts to atone for her actions. Her only friends are the counterparts of Rainbow Dash, Applejack, Pinkie Pie, Fluttershy and Rarity, who have formed a rock band called "the Rainbooms" to participate in the school's upcoming musical showcase. The five girls discover that the magic left over from Twilight's crown has given them the ability to grow pony-like ears, tails, and wings whenever they play their instruments.

Hoping to make a fresh impression, Sunset gives a school tour to three new students – Adagio Dazzle, Sonata Dusk, and Aria Blaze – and informs them of the showcase, unaware that they possess magical singing voices. Calling themselves "the Dazzlings", the trio perform a song that turns the other students aggressive and competitive towards each other, convincing them to turn the friendly showcase into a Battle of the Bands. Sunset and her friends are protected from the song by their own magic, but fail to convince the bewitched Principal Celestia and Vice Principal Lunaof the danger. Sunset remembers a book that magically copies whatever she writes in it to another kept by Princess Celestia, her mentor from the parallel world of Equestria, which she uses to send a message requesting Twilight's help.

Princess Celestia's book is delivered to Twilight's castle in Ponyville. Receiving Sunset's message, Twilight deduces that the Dazzlings are banished sirens from Equestria that feed on negative emotions to fuel their singing powers for their goal of world conquest. Twilight uses the book's magic to reactivate the portal between worlds, allowing her and Spike to return to the parallel world. Twilight and the girls attempt to use the magic of their friendship to lift the Dazzlings' spell, but it takes no effect. Concluding that they must perform a musical counter-spell, the girls enter the Battle of the Bands to give Twilight time to complete the spell. The Rainbooms face hostility and sabotage from the bewitched bands throughout the competition, which raises existing tensions among Twilight's friends over conflicting aspects of their band.

Desperate for time in the semifinal round against Trixie's band, Rainbow Dash performs an egotistical song to substitute the counter-spell and nearly transforms, which forces Sunset to ruin her performance to keep her from exposing their plan to the Dazzlings. Despite this, the Dazzlings intervene to allow the Rainbooms' advancement to the final round, goading a jealous Trixie into trapping the Rainbooms beneath the stage to take their place. Isolated for hours, Twilight's friends enter a heated argument that allows the Dazzlings to absorb their magic. Realizing that their constant infighting is interfering with Twilight's spell, Sunset convinces the girls to resolve their differences, while Twilight reasons that simply playing together as friends will make the counter-spell work.

Spike rescues the girls with assistance from DJ Pon-3, a student whose headphone music protects her from the Dazzlings' spell. DJ Pon-3 provides a sound system that the Rainbooms use to engage the Dazzlings in a musical battle. Overwhelmed by the Dazzlings' projected siren forms, the Rainbooms are joined by Sunset, who assumes her own pony-like form; with her help, the Rainbooms are able to destroy the pendants that provide the Dazzlings with their singing abilities, rendering the trio tone-deaf. Returning to its harmonious state, the school drives the Dazzlings away and praises the Rainbooms. Twilight and Spike return to Equestria, while Sunset uses Princess Celestia's book to remain in contact with Twilight.

During the closing credits, a montage plays showing Sunset being accepted by the student body and performing as the Rainbooms' new lead singer and guitarist. In a post-credits scene, the human world's version of Twilight Sparkle is shown investigating the strange activity around Canterlot High.

Trivia

 * Team Griffin/Eeveelution, The Griffin Family, Vinny Griffin, Glenn Quagmire, Cleveland Brown, Joe Swanson, Roger Smith, Bender Bending Rodríguez, and Minerva Mink guest star in this film.