What happened to g4 that lead to g5

Twilight was having a magic lesson when her magic went out of control & teleported herself to the moon & was face to face with Nightmare Moon.

Twilight finds weird gem which sends her back in time up about 200 years before discard came into the picture What she finds in the past will change her life forever

Celestia with her faithful student Twilight goes to her school for gifted unicorns to grade the projects for the midterm exams but something goes wrong and now Celestia is turned into a filly Can she turned back to normal before nightmare moon return

The stories up about twilight and the three other princesses getting together in her castle wow her brother the rest of the main six and big Mac follow the cutie Mark crusaders to get to Zecora who is watching over a strange item in the everfree