In an alternate unvierse, Cadence,sells her identify to Chrysalis the Changling Queen. A story inspired by Disney's The Little Mermaid, but not a direct retelling of it with ponies.
The spell that was undone by Twilight actually only cured poor Fluttershy temporarily. Now she is a perminment Vampire Fruit Bat Pony hybrid. Princess Celestia thus has ordered to move Flutters away from her friends to ensure that no one else get&
When Sunset Shimmer steals Twilight's crown she ventures into a new world with humans who play card games. She then meets Yugi Moto and his friends. In order to win her crown back she must beat the best of best including Sunset Shimmer.
With Twilight now being a full on princess she has to grasp the new responsibilities she has been given with. She now has to balance these duties with her friends back in Ponyville . At first she is ok with the balancing this but sooner or later she
Princess Luna gets corrupted by Discord into becoming Nightmare Moon once again, and its up to her sister to show her true love to save her from Discord.