He only does crimes in an AABBA pattern, and he wears a bright yellow suit covered in Edward Lear illustrations, and his real name is like Poe Atree or something.
There once was a Batty from Gotham
And criminals he did try to stop 'em
But he never did see
His incompetency
And forgot to check on his Robin
Comic panel shows the newest Robin dangling over a vat of lime green acid while The Limericker dances an Irish jig on the rope.
Riddle me this batman, there once was a man from nantucket
That's just a combo of the Joker and the Riddler, which is why it absolutely would work as a Batman villian
Batman: Alfred, the Limericker keeps sending me dirty poems.
Alfred: You know, master Wayne, My country knows more than anyone about how to deal with the Irish.
Batman: Alfred, that's fucked up. Gotham is like 50% Irish, you know that, right?
Alfred: chuckles In for a penny, as they say, master Wayne...