Based on the story by Magpiepony. Check it out here.

Now in possession of the Alicorn Amulet, the vile pony known as Astelle is practically unstoppable. With the Mane 6 and the Princesses defeated, she now plans to kill the Tree of Harmony and bring Equestria into a "New Era" of darkness and free of magic. Only one can save all of ponykind now...

An AU for the story created by DisneyFanatic2364. You can find it here.

In the city of Maretropolis, crime runs rampant. Superpowered villains roam the streets terrorizing innocent civilians. However, one night, after a dastardly act of evil was committed, six unlikely allies came together to combat crime and injustice in the city. They were the Power Ponies, and they proved to be the heroes the city needed.

...or at least, that's how things were supposed to happen. However, the events were changed by the very presence of a single pony. A pony with the power to defeat all of his foes with just a single punch.