This story takes place after Twilight has become an alicorn. Celestia notices that Twilight is starting to feel the pressure of her new role. So, Princess Celestia decides to raise Twilight's spirits by bringing the Autobots to Equestria.

Chronologically, this takes place some time after Magical Mystery Cure for the MLP side. As for the Transformers' side, well it's not based on any particular continuity or story. It's really more based around MLP/TF crossovers in general. I hope you all enjoy!