Rarity comes up with the idea of rallying the students by encouraging them to wear the Canterlot Wondercolts' pony-eared headbands and tie-on pony tails. When Twilight helps the five reconcile their differences, they help her get voted Princess of the Fall Formal. Rarity and the rest of Twilight's new friends are later revealed to have been driven apart by Sunset Shimmer she is particularly bitter toward Pinkie Pie. Rarity pulls Twilight into an empty classroom and gives her a disguise.
In My Little Pony Equestria Girls, Rarity first appears after Sunset Shimmer ruins Twilight Sparkle's image at Canterlot High with an online smear video.
1.4 Equestria Girls: Legend of Everfree.