Pooh's Adventures of Batman: Arkham Asylum is a Winnie the Pooh/Batman movie by N/A
After the Joker assaults Gotham City Hall, he is caught by Batman and escorted to Arkham Asylum, which temporarily holds many members of the Joker's gang, displaced by a fire at Blackgate Prison. Believing the Joker allowed himself to be captured, Batman accompanies him into the asylum. The Joker's plan is revealed as Harley Quinn takes control of the building's security and the Joker escapes his captors, aided by a corrupt guard who kidnaps Commissioner Gordon. The Joker threatens to detonate bombs hidden around Gotham City if anyone tries to enter Arkham, forcing Batman to work alone. While pursuing Quinn to rescue Gordon, Batman is exposed to the Scarecrow's fear toxin and hallucinates, seeing the corpses of his parents talking, and Gordon's death. Batman fights off Scarecrow and the toxin's influence, and eventually navigates his way to a secret Batcave installation he had hidden on the island, where Batman restocks his gadgets.
Batman finds Quinn, knocks her unconscious, and rescues Gordon. The Joker then directs Batman to the captured Bane, who has been experimented on by asylum doctor Penelope Young. Batman frees and subsequently fights Bane, and learns that the Joker has returned to the asylum to gain access to Young, who has been developing Titan—a more powerful version of the Venom drug that gives Bane strength—intending to use it to help patients survive more strenuous therapies. Young learns she has been working for the Joker and refuses to hand over the Titan. The Joker plans to use the Titan to create an army of superhuman henchmen. While searching for Young, Batman is again attacked by Scarecrow and the fear toxin, and hallucinates his parents' deaths. After he recovers, Batman destroys Young's Titan formula and rescues Young from Victor Zsasz. An explosion kills Young and the Joker obtains the completed batches of Titan.
Quinn releases Poison Ivy from her cell and later fights Batman, but is defeated and imprisoned. Quinn inadvertently reveals that Joker has a Titan production facility in the Arkham botanical gardens. Batman travels there and learns that Titan is created by genetically modified plants. He tries to enlist Ivy's help to create an antidote, but she tells Batman that an antidote can only be made from spores found exclusively in Killer Croc's cell in a sewer. En route to Croc, Batman is again attacked by Scarecrow and overcomes several doses of the fear toxin. Meanwhile, Joker injects Ivy with Titan, enhancing her powers. Ivy begins ravaging Arkham Island with giant mutant plants and vines. Pursued by Batman into the sewers, Scarecrow is attacked by Croc. Batman recovers the necessary spores and subdues Croc before returning to the Batcave; he can synthesize one dose of the antidote before Ivy's plants breach and destroy the cave.
Batman returns to the botanical gardens and defeats Ivy, ending her destruction. The Joker announces that the preparations for his party are finally complete and Batman travels to the asylum's visitor center where the Joker's applauding henchmen welcome him. The Joker reveals he has recaptured Gordon and tries to shoot him with a Titan-filled dart; Batman leaps to Gordon's defense and is shot instead. Batman attempts to resist the change, and the Joker becomes upset and takes an overdose of Titan, mutating into a massive monster. In a makeshift arena on the building's roof, the Joker challenges Batman to a fight as Titan-induced monsters in front of news helicopters. Batman refuses to transform, uses the antidote on himself, and defeats the Titan-affected Joker and his henchmen, knocking his nemesis unconscious with an explosive gel-enhanced punch. In the aftermath, those affected by Titan begin to revert to normal, including the Joker—who is restrained and taken into custody as police officers retake the asylum. As Batman leaves, he overhears a call about a crime led by Two-Face in progress. In a post-credits scene, a crate of Titan formula is shown floating in the ocean around the asylum when a hand surfaces and grabs it.