Friendship is Magic: Hit the Books!
A videogame where you control the Mane 7 (or a smaller group of them) and use their various skills in conjunction to make their way through an environment.
From a technical standpoint, it would probably make the most sense to have it as a 2D-side-scroller (that turns into a top-down exploration game when using any of the fliers abilities). This could be explained away in-story by the Mane 7 being trapped in the pages of a book and taking graphical cues from games like Paper Mario and Yoshi’s Story.
One of the Mane 7 would be your “jack-of-all-trades” character (Twilight? Spike?) with a well-rounded skill set.
Rainbow Dash is the fastest and can fly anywhere, turning the game from a side-scroller like Super Mario Bros. into a top-down exploration game like the NES Legend of Zelda. I imagine there’s something limiting her (or at least buffing the other characters) to keep her from being the only character you need. Fluttershy and Twilight can also fly, but can’t control as solidly or move as fast as Dash. FS and Twi probably have some other ability as well, like animal empathy and teleportation spells.
Pinkie might be able to “float” Rayman-style by summoning a ton of balloons to hang onto. Technically, Rarity could also have something like that, by using a parasol like Princess Peach. AJ obviously has some sort of lasso-grapple ability that makes platforming easier for her and perhaps can make plants grow to open up new passages. Spike is fairly limited vertically, but has a ton of cool dragon abilities to use: flame breath, gem-munching, strength, impervious to lava and needles, etc.