The Third Street Saints have fought many different types of enemies:street gangs, international syndicates, terrorists, even aliens, but when the Boss is transported to Equestria, they will face an entirely new challenge:
Walking on four hooves.
The Boss will join up with the Mane Six to take down the gangs that have taken over Equestria, and return the crown to Princess Celestia.

The Boss in this will be addressed in "They" because the Boss is what YOU want them to look like.