Some TMNT stuff really isn't for little kids.
The Mutanimals were co-founded by Old Hob and Slash. Hob used a supply of mutagen to create Pete, but deemed him inadequate, so he recruited Lindsey Baker to help him create Herman and Mondo Gecko and to properly use Splinter's mutagenic blood to give Slash normal intelligence. From here, the Mutanimals were formally organized with the goal of protecting vulnerable mutants from exploitation and harm.
In Teenage Mutant Ninja Turtles: Mutanimals, the Mutanimals came into conflict with Null's Null Group. In an assault on Jillian Amante's lab, they rescued Mutagen Man and brought him into their group. Soon after, they freed the Null Group's surviving mutants, Sally Pride and Ray, from a Null Group train at a rail yard in New Jersey. The Mutanimals and Null reached a stalemate, unable to completely defeat each other, but the Mutanimals succeeded in derailing the Null Group's mutant experimentation projects by applying enough sabotage and blackmail to make them unworkable.
After Splinter became the new leader of the Foot Clan, Michelangelo left his father and brothers, wanting nothing to do with the Foot as an organization. In issue 52, Mondo Gecko tracked down Mikey, and in issue 53, Mikey was welcomed into the larger Mighty Mutanimals as their newest member. He took part in one of the Mutanimals operations before stumbling over Hob's secret. After this, both Mikey and Slash left the Mutanimals; Mondo, Sally, and Seymour lost some of their confidence in Hob; and Mikey earned Hob's renewed enmity. Mikey offered Slash a new home, but Slash decided he needed to be on his own and learn what it's like to be the master of his own life, and the two tearfully parted ways. While Slash and Hun are still enemies, Slash remains on good terms with Hob, the other Mutanimals and Mikey.
In issue 65, Slash arrived unannounced to Michelangelo's Christmas party, followed soon after by Pete, Lindsey, Herman, Mondo, Seymour, Ray and Sally, none of whom had been invited. (Hob and Hun did not come.) The party that followed showed they were all still on excellent terms.
In Teenage Mutant Ninja Turtles Universe issue 5, on the same Christmas Eve, Hob discovered that Hun had started an unsanctioned dogfighting ring in Hob's weapons warehouse. Meanwhile, Leatherhead also independently discovered the dogfighting ring, disapproving of the dogs' treatment. In the ensuing conflict, Hun quit Hob's service and fled the scene. Hob was initially fond of Leatherhead, who nostalgically reminded him of Slash, so Hob tried to recruit the alligator into the Mutanimals. Hob tried to sell his philosophy that all mutants are a family in conflict with the human world, but Leatherhead opined that all of them (Leatherhead included) were monsters with no place in the natural world, and the two started fighting. During this conflict, one of Hob's grenades detonated his weapons cache, destroying the entire warehouse, with Hob and Leatherhead separately escaping with their lives. When Hob returned to base, no one else was home—the other Mutanimals had gone to Michelangelo's Christmas party.
In TMNT issue 67, Slash was captured by Agent Bishop and brainwashed to raid the now thoroughly compromised Mutanimals base, capturing the entire team except for Hob. Mondo's tail and Herman's left claw were violently severed and Seymour's body tank shattered during the brief but violent assault.
In issue 68, Hob entered the turtles' lair uninvited, announced his presence and asked them for their aid rescuing his team, though making it clear he still despised them and Michelangelo especially. In Agent Bishop's custody, a captive Lindsey was assisting a medical team saving Seymour's life, while another medical team were giving Herman a new prosthetic claw as the severed claw could not regenerate. Mondo's tail was, however, in the process of naturally regenerating itself. Bishop's team discovered Ray and Sally had significant signs of posttraumatic stress disorder (PTSD) from their past in Null's captivity, while Mondo was relatively mentally unscarred, and the eccentric Pete could not be psychologically evaluated at all. During an antagonistic exchange of words with Bishop, Ray revealed that he had once been trained as a soldier, and demonstrated this by revealing he had freed his and his friends' restraints, and used previous unknown stingray barbs on his wings to attack some of Bishop's subordinates. But in actuality, it was a diversion to allow Sally and Mondo to escape unnoticed, though Pete did not flee with them. Sally stole a bullet-proof vehicle to crash out of the facility. Hob and the turtles visited the now trashed Mutanimals base looking for clues, only to realize too late it was still being surveiled by Alex Winters and his forces.
The Mutanimals have had a complicated membership history.
- Old Hob and Slash (former member) were the co-founders of the group.
- Pete was mutated by Hob and became the group's cook.
- Lindsey Baker is a non-combatant human scientist recruited by Hun.
- Herman and Mondo Gecko were mutated by Lindsey.
- Seymour Gutz was rescued from a Null facility, shortly before Man Ray and Sally Pride were rescued from a Null train yard.
- Hun (former member) was secretly recruited by Hob, Herman and Ray without the knowledge of the other Mutanimals, to sell for profit the surplus of the weapons the Mutanimals had been seizing and Hob said were being destroyed.
- Michelangelo (former member) was once recruited by Mondo Gecko and participated in one Mutanimals operation.
- In earlier issues, unlike other versions of the Mighty Mutanimals, this version of the team was formally just called the Mutanimals, without the word "Mighty." However, in issue 2 of the Mutanimals miniseries, Slash tells Mondo Gecko, "We're gonna be the mighty Mutanimals!", an easter egg in reference to the longer title. Starting with TMNT issue 53, Hob started using the title Mighty Mutanimals more formally.