From Kingdom Hearts Wiki: A world of information not accessible by Gummiship
In the 100 Acre Wood Command Board, Rabbit is seen briefly in the cutscene shown when stepping on a special panel. He finishes stacking pots of hunny into a pyramid and then runs away from a large pumpkin rolling down the hill which destroys the pyramid.
Ten years later, Rabbit is seen with Pooh who wishes to get Hunny from Rabbit. Rabbit pretends nobody is at home but Sora discovers Rabbit and Pooh ends up with Piglet helping himself to some hunny. Pooh then gets stuck in Rabbit's hole door while he is trying to leave, Rabbit says the way to get him out is to use carrot juice. But when Rabbit goes to collect the carrots, Tigger comes to use his garden as his new bouncing ground, this makes Sora go to protect it. Rabbit is also seen with his friends at the last page of the 100 Acre Wood. You can also pull Rabbit's cabbages and pumpkins out of the ground and items will occasionally pop out.
Rabbit is one of the friends Sora must find for Pooh to complete the 100 Acre Wood World Card. He is busy trying to carry his vegetables down a hill when one of his pumpkins gets loose and bowls over Pooh. Sora stacks the rest while the continue to roll down the hill. Once Rabbit races down, he sees that the vegetables have been stacked and thanks Sora with the Sleight, Synchro. In Kingdom Hearts Re:Chain of Memories, you receive the Cross-slash+ sleight instead.
Rabbit tries to help Pooh remember Sora in Kingdom Hearts II by feeding him Hunny. When he runs out, asks Sora to get some more which leads to the "Hunny Slider" minigame. He shows up to help in the Spooky Cave but does not go in with Sora during "The Exposition" minigame.
Rabbit is a large, anthropomorphized hare with predominantly yellow fur, except for his belly, mouth, and tail, all of which are white. He has long ears that are pink on the inside, four-fingered hands, and large, three-toed feet. His nose is round and pink, and he has four black whiskers, two on either side of his upper lip. He also has oval-shaped, black eyes and brown eyebrows.
Rabbit is practical in all matters and keeps his friends on the go. Rabbit at times may come across as being stubborn when it comes to his viewpoints, but once he realizes his mistake, he has the ability to admit he was wrong. He also tends to overreact in haste, but all his friends know that under his slightly bristly exterior lies a good heart. He likes to organize things and stay busy, hence he is often found tediously working in his garden.