They initially are disguised as humans with small dogs strapped their chests. Upon confronting the Ninja Turtles, they reveal their true monstrous forms and the dogs are transformed into battle mounts.
The Guardsmen are servants of Baron Draxum. They are first seen chasing after Mayhem when they run into the Ninja Turtles at a construction site causing the Guardsmen to shed their human forms. After a brief fight, the Guardsmen escape into a portal to the Hidden City where April O'Neil and a food deliveryman named Stewart unknowingly followed them into.