Batgirl (Batman vs. TMNT)

"Retro Mutagen and it's right here but it's untested it could kill him."

- Batgirl to Donatello.

Barbara Gordon fights crime as Batgirl, one of the proteges of the Batman, in Batman vs. Teenage Mutant Ninja Turtles.

History
In her civilian guise as Barbara Gordon, Batgirl was present at Powers Industrial when the Foot Clan invaded to steal an experimental generator. She witnessed the Ninja Turtles entering the fray, but mistakenly believed that the "lizard men" were allies of the Foot rather than enemies, and that they had taken the generator.

She later met up with Batman at Wayne Enterprises, where he informed her that her "lizard guys" were in fact giant mutated turtles, and she deduced that some of the stolen technology could be used to refine mutagen. After she expressed disappointment that he hadn't called her in before, he said that he could use her help.

She accompanied Batman back to the Batcave, where they found the Turtles fighting Robin. After the two groups made peace, she quickly bonded with Donatello as the two worked together to create a retromutagen. The pair were soon able to create a retromutagen or "anti-ooze," but Batgirl cautioned that it was untested, and had a 40% chance of lethal side effects.

When Michelangelo and Alfred Pennyworth arrived with several pizzas, she began eating a slice, but reluctantly abandoned it when Batman told her that she should be working.

When Shredder and Ra's al Ghul invaded Arkham, she accompanied, Batman, Robin and the Turtles to meet her father, Commissioner James Gordon. She accompanied the group to Arkham, where she and Donatello were one of three groups that split off to search for hostages.

They soon ran into Bane, whom the Joker had mutated into a jaguar. He dragged them through a wall into the facility's gymnasium, where Donatello was temporarily knocked senseless and Batgirl was forced to dodge thrown punching bags. She was hit by one and temporarily rendered unconscious, but awoke in time to smash a hand weight against his face, knocking him out.

Batgirl and Donatello reached the others just as Batman was injected with a mixture of mutagen and Joker Venom, causing him to turn into a crazed bat mutant. Fortunately, Batgirl had a dose of the retromutagen on her person, but she was apprehensive, since it could potentially be lethal. After Leonardo failed to dose Batman, Batgirl was forced to fight the Joker in order to secure the cure. Eventually Batman was restored to normal, and Batgirl knocked out the Joker's teeth before taking a selfie with the dazed psychopath.

While Batman recovered, Batgirl explained to the Turtles that the components of Joker Venom could be found at Ace Chemicals. When the Batmobile and Turtle Van were dispatched to the chemicals company, she rode in the Turtle Van, and she and Raphael rode their motorcycles into battle with the combined Foot and League of Assassins ninja. One foe in particular was a mutant elephant, whom she provoked into following her and tricked into ramming explosive chemical trucks.

Batgirl then joined the Turtles, Batman and Robin in fighting the League and Foot ninja, and eventually fighting Ubu until she kicked his head against a railing. She later appealed for help in carrying him from the building, due to his greater size and weight.

Back in the Batcave, she and Donatello exchanged social media information, before settling down to eat some pizza that Batman had procured.

Trivia

 * Her online handle is Oracle, the heroic persona she take up after The Killing Joke.
 * One running gag is Batgirl's antipathy for the word "ooze," which she refuses to use.