The Jokerz.

One of the least deadly but most annoying criminals in future Gotham, they are often related to cock roaches. You step on one and ten come out of no where. They just keep coming, and coming, and coming, and coming, and coming....

Terry McGinnis's first real encounter with this gang was while he was riding on his motorcycle one night and they knocked him down.
Sorely out numbered, Terry probably would have put up a fight, but lost anyway and beaten near, if not to, death. But then came old Bruce Wayne. After a fight with them, they scampered off into the wilderness where all Jokerz go.
Another time was when they were purchasing heavy artillary and Batman... Intervined.
Then they approached deadly enemy Willie Watt, the high school nerd turned mega creature after being practically fried to a giant robot mentally. Once again, they were scared away.

Exactly like their inspiration, these little bugs don't know when to stop. And until they do they'll just have to put up the cops and Batman.