The story is generally the same. A group of ponies go on a quest to stop an insane alicorn who had escaped banishment, learning about friendship along the way and mastering the Elements of Harmony. But the details...

It can be Trixie Lulamoon leading the Elements of Harmony against Corona.
Rainbow Dash could be Celestia's student and go to Ponyville.
Equestria could have a deep connection to three young people in its distant past.
The Elements of Harmony could have been moved to Manehattan for the ponies to quest for.
Princess Cadance might rule over an Equestria of music, with Octavia as her prized protege.
Or Spike and Twilight might have their roles reversed, the former a stallion and the Element of Magic.

And each one has been chosen by Discord, an Element removed to a seventh Equestria for purposes as yet unknown. Can they survive? Can they get home? Read and find out!

The Lunaverse was created by RainbowDoubleDash and is used with permission. Opening segment was written by Talon and Thorn.
The Hasbroverse was created by RK_Striker_JK_5 and is used with permission.
The Manehattanverse was created by Little Jackie Papercut and used with permission.
The Cadanceverse was created by GrassAndClouds2 and used with permission.
The Flipverse was created by Bed Head and used with permission.
The Dashverse was created by Trinary and used with permission.

And special thanks to dramatic_spoon for getting this all together.