The MGH, the Multiverse Guardian Hub, is the largest organization in existence simply because it encompasses all of existence.

Its members are made up of beings from different Universes that help make sure things run smoothly in the Universes under their care.

This is a story involving the adventures of one squad within the Pony Division of the Hub as they train their newest member and make sure the Universes in their Cluster are the way they're supposed to be.