Did you look for the episode called Lego Batman - The Villains?
The Villains is the name commonly given to the several gatherings of supervillains present in the ForrestFire101's Lego Batman series of videos.
The Villains is the name of countless gangs of supervillains antagonising Batman & Robin. The villains appear to be severely underfunded, as they usually work out of decrepit stone buildings and having to resort to measures such as killing teammate Mr. Freeze in order to avoid buying another gun. The gang also seems to have quite a lot of internal struggle, as members usually argue about methods and goals. However, as The Joker usually is the ringleader, the caotic state of the team is not at all suprising.
As the Villains' membership fluctuates and changes from episode to episode, a definitive list of membership is impossible to discern. This list will contain the regular villains most often found in the gang.