Abu

Abu is Aladdn's pet monkey, and he lives in Agrabah. He is often seen getting into constant trouble every now and then. He is only seen a few times in the game getting Sora and friends in trouble in the Cave of Wonders. He has a bad habit of stealing things. Sora uses the "Call" Reaction Command to call Abu to a statue with a jewel in its hand to activate the jewel. The activated jewel usually opens a passage or moves a pillar.

Kingdom Hearts
''Aladdin's faithful furry sidekick. Abu's size and ability make him valuable in tight spots. He's got a weakness for jewels and treasure, and when he's around them he can't think of anything else. He was all monkey-business in "Aladdin" (1992).''

Kingdom Hearts II
Aladdin (1992)

''Aladdin's faithful and rather furry sidekick. Abu doesn't talk a lot, but he always understands what Aladdin needs.''

Unfortunately, Abu can't resist treasure, even if it belongs to somebody else.

Trivia

 * In the Kingdom Hearts II's Cave of Wonders, Abu is an half-playable character (you play as Sora too): you must put a jewel, with the reaction commands.