Joker's Royal Flush Gang
The members of the first Royal Flush Gang were subjects of United States government metahuman research. The Joker freed them from a government facility, and formed the group. Dressed up as playing cards, the Royal Flush Gang did the Joker's bidding.
Ace's Royal Flush Gang
Another Royal Flush Gang was controlled by Ace, the mind-controlling girl from the first gang. After her death, the real "illusions" that Ace was projecting disappeared, leaving this new gang powerless.
The family of crooks known as the Royal Flush Gang preyed on Gotham City during Terry McGinnis' tenure as Batman. The gang utilizes weapons shaped like playing cards and flies across the city on card-shaped boards. While they don't have any superhuman powers, King is a master swordsman and Ace is an artificial human. Ten, the daughter of the bunch, is torn between her gentle and ruthless sides, and develops a rather unprofessional relationship with Batman. Queen alluded to the fact that positions on the gang have passed down her family line, with her father being the previous "King" of the group.