Thany you, JimmyHook19, for suggesting this! Just after hearing this...I might have something to involve one more princess other than Twilight.
Yes, Twilight became the ruler of Equestria. But what if she disagreed to Celestia's offer? I think Luna could be possible since she didn't have a chance to rule in a good condition. But wait...How about other creatures? Not to be racist or anything but also creatures didn't have a chance to rule Equestria aside from where they are from. Maybe a video could help solve with me too...?