It's part of an elaborate storyline from Grant Morrison.
"Batman of Zur-En-Arrh" is Bruce Wayne's "back-up psyche" in case the persona of Batman ever gets traumatized to the point of not being functional. He's basically the embodiment of what Bruce Wayne wishes for Batman to be (He dresses like he got his laundry mixed up because he is completely and utterly fearless) and completely ruthless (his weapon of choice is a Baseball Bat) and he takes orders from Bat-Mite.
It's actually a really cool story and concept, but it probably won't make a return anytime soon.
“I have never listened to anyone who criticized my taste in space travel, sideshows or gorillas. When this occurs, I pack up my dinosaurs and leave the room.” - Ray Bradbury