Based on the Impostors arc from DC comic's Detective Comics #867-870, which is partly based off the Jokerz gang from Batman Beyond and Sons of Batman from Dark Knight Returns. The set up is basic, batman's out of town so "The Bats", a bunch of Average Joes dressed up in their own ghetto versions of the cape and cowl, get a bunch of guns and attempt to protect the city. At the same time, a bunch of dudes who are joker-obsessed dress up like the clown and of course them and the Batmen come…