"For generations, life on Earth-8 passed like it does on our world. Largely uneventful, and when problems did arise, they were handled easily by the world’s large population of super heroes. Until a day finally arrived like no other, and Earth-8’s strongest heroes were forced to unite against a common threat. The Retaliators were born!"Not quite what you were expecting?
The Retaliators were created by Grant Morrison during his Final Crisis multiverse epic, and later re-appeared in The Multiversity. The name is a play on The Avengers, Marvel's premier super-hero team. Each member is based on a corresponding Marvel character as they exist on Earth-8.
As with the heroes of Earth-0, their adventures are fiction published in other parallel worlds under the Major Comics editorial label.
Briefly seen in Final Crisis, (where they were wrongly described as from Earth-6), the Retaliators and other heroes of their world were amidst a civil war instigated by a group of secret invader shapeshifting aliens. Apparently, they overcame those crises to return to a happier status quo.
Traditionally, the Retaliators had been lead by American Crusader, an ages-old supersoldier and their membership includes the technological armored Machinehead, the thunder wielder Wundajin, the quick to rage Behemoth, the beauty and deadly Red Dragon, the cosmic-powered Major Max, the accurate bowman Deadeye, the athletic Ladybug and the aerial Kite.
The Retaliators, (along with the rest of Earth-8) were heavily featured in Multiversity as one of the Earths attacked by the Gentry, using a brainwashing Nix Uotan as their conduit. The Retaliators had to use all their resources and the help of their world's other teams (G-Men and Future Family) to stop the attack from another reality, which includes the zombie versions of alternate doppelgangers from the Retaliators themselves. Only with the help of Thunderer (Wundajin's doppelganger) and Aquawoman from Earth-11, the Retaliators had a chance to stand against the Gentry attack.
After foiling the invasion of the Gentry, Machinehead chose to stay with the extradimensional peacekeeper force to thwart any further attack.
The precedent of the Retaliators were the Champions of Angor, a direct answer to Marvel's Squadron Supreme. Another parallel was the Maximums, more closely inspired in the Ultimates. Several concepts of the Champions of Angor are still present in the post Flashpoint Earth-8. The superheroes from Earth-7 also resemble not only Marvel characters but from other publishers as well.