Justice League (2001)

Season 1: Episode 16

Exposed as a criminal, sentenced to prison, and terminally ill due to long term kryptonite exposure, Lex Luthor escapes and assembles a supervillain team consisting of Cheetah, The Shade, Solomon Grundy, Star Sapphire, Copperhead, and Ultra-Humanite to take on the Justice League, calling themselves the Injustice Gang. The Joker also becomes part of the team, but on his own choice. However, this gang proves short-lived as its major weakness proves no match for Batman's wiles.