Joker's Gang (DC Extended Universe)

The Joker's Gang is a criminal organization composed of primarily insane and dangerous criminals led by the Batman's archenemy The Joker. They are the most powerful criminal organization in Gotham City, as Joker is the "King Of Gotham" and rule the city's criminal scene. In honor of their leader gang members dress colorfully and flamboyantly whose personal style is just as flamboyant and colorful. In Suicide Squad, particular thugs in his criminal empire are the thugs he takes on his personal mission of saving his lover/partner Harley Quinn from Task Force X.

They are a minor antagonist group in the DC movie Suicide Squad.

Overview
It's unknown how the Joker's gang came to be but is known the clownish madman upset the order established by the Falcones and Maronis and would begin to rise in GC's underworld. Jonny Frost would join the gang sometime early on in the gang's creation and eventually become Joker's no.1 man in the syndicate. Presumably the gang would topple all other villain's criminal empires, aiding Joker become the city's top crime lord while having encounters with Batman.

Particular members of the gang dressed in flamboyant outfits would lend a hand in the creation of Harley Quinn shortly upon freeing The Joker from Arkham Asylum.

Suicide Squad
In present day Joker is depressed his fling/lover/partner is gone from his life for quite some time and has Frost look for her. By bribing some high-level officials Frost learns Quinn is held in a maximum prison facility in the Louisiana swamps and informs his boss who acts fast to save his lover. Joker and his thugs travel across the country to get a prison official, Griggs, to help them in Joker's plan. They learn of Task Force X and nano-bombs and later attack Van Criss Laboratories to force the inventor of the nano-bombs to help them save Harley.

They hijack a military helicopter in Midway City in effort to save Harley but are shot down by the US Military, killing them all while Joker and Harley survive.

When Harley is returned to her cell in Belle Reve after she helps the Squad kill Enchantress and Incubus, with her little reward, Joker and another gang of thugs attack the complex, killing several guards and free her form her cell with Joker and Harley reuniting.

Members

 * The Joker: Founder and boss ("King of Gotham")
 * Harley Quinn: Joker's lover/partner ("Queen of Gotham")
 * Panda Man
 * Crying Baby
 * Eyeball
 * Shark 1
 * Shark 2
 * Sea Urchin
 * Batman (thug)
 * Goat
 * Muscle Man
 * Pedro The Cleaner
 * Several other thugs and henchmen, including the group present in Harley Quinn's rescue from Belle Reve.

Trivia

 * The gang is never once referred to in the film, but are mentioned in the novelization of the movie.

It is unclear whether the group accompanying Joker in his quest were merely hired goons/mercenaries since the birth of Harley Quinn and not official members in Joker's gang or if they're really part of the gang. Also, since they're never referred to outside of Amanda Waller's throwaway quote that Joker is "King of Gotham City", it is most likely they have loyal enough goons to accompany him in a personal mission such as saving Harley from a dangerous scenario. It is very likely he has far more formidable thugs and mercenaries back in Gotham City and are part of a large and powerful criminal empire.