(set immediately "Even Further Consequences") It took a lot of hard work and quite a bit of help (particularly from Sunset, Flash, Starlight, Doctor Whooves, Zecora, Celestia, Luna and Discord), but the Mane Six DID manage to beat the alternate timeline versions of Sombra, Chrysalis, Nightmare Moon, Discord, Tirek and the Flim Flam Brothers. Now, with the further help of Doctor Whooves and TARDIS, the Mane Six return the defeated villains to their own time lines and start helping the locals in each time line start the healing.
What if it turns out that Nightmare Moon wasn't evil.
And Nightmare Moon did more good than bad.