The Justice Ducks are a group of superheroes from St. Canard.
A group of superheroes, the Justice Ducks were formed in response to the threat posed by the Fearsome Five, led by Darkwing Duck's evil counterpart Negaduck. The individual came together in the midst of the villains' activities, with Gosalyn Mallard proposing that they form a team. However, the egotistical Darkwing was against the idea of a teamup from the start, believing himself equal to the task of defeating the allied villains and not wishing to share the glory with anyone. His pride proved to be his downfall, as his solo assault upon the Fearsome Five ended disastrously.
The rest of the proposed members of the Justice Ducks were themselves defeated and captured when they individually challenged members of the Fearsome Five. Darkwing, humbled and now ready to accept help, was thus forced to infiltrate the lair of the Fearsome Five to free the others. Working together, the first five Justice Ducks were able to overcome the Fearsome Five and apprehend them.
The Justice Ducks were later reformed (Darkwing having lastingly swallowed his pride and accepted the idea of teamwork), fighting the Fearsome Five and other villains with a flurry of new heroic recruits, though Darkwing eventually returned to solo work.
Behind the scenesEdit
The Justice Ducks, a riff on "serious" superhero teams like the Avengers or the Justice League, debuted in the 1991 Darkwing Duck two-part episode Just Us Justice Ducks. A recurring joke in the episodes where the team was featured was that, though the team is named "Justice Ducks", Neptunia and Stegmutt are not actually ducks (though, as Stegmutt points out, he at least was originally a duck).
There were once plans for a spin-off of Darkwing Duck entitled Justice Ducks, focusing on a retooled version of the Justice Ducks team (swapping out all but Darkwing Duck and Gizmoduck for all-new characters, most being parodies of other popular "serious" superheroes). However, the series was never produced, and all that remains is concept-art. 
A similar group appeared in the Darkwing Duck episode Darkwing Doubloon, in which they served as the crew of the titular pirate hero's ship. However, this team differed from the Justice Ducks in that Launchpad McQuack and Gosalyn's counterparts were full members, while no counterparts of Morgana or Neptunia were present. Additionally, Gizmoduck's suit was made out of technology and armor appropriate to the era.
Another similar team, the Ultraheroes, were later introduced in Disney comics.