First appearing in the season 5 episode’ “Brotherhooves Social”, and having a speaking role in Triple Threat and Horse Play, Rainbow Star is one of the background ponies as well as several characters who first appeared in the fifth season to appear in the show’s final seasons plus Best Gift Ever. But she didn’t appear in either Rainbow Roadtrip or the movie. Speaking of the movie, I believe that she was one of the ponies present in Canterlot during the events of movie when the Friendship Festival is happening ijnCanterlot but got later ruined, or disrupted, or cut short by the Storm King who conquers Canterlot and to the rest of Equestria, and after when Equestria is saved and restored back to normal after the Mane Six and their new friends they’ve made from Beyond Equestria defeated the Storm King and his Storm Army and the Friendship Festival resumes.