AiAi

Aiai is the main character in Super Monkey Ball. He has appeared with Sonic several times, most notably in Sonic Riders, Sega Superstars Tennis, Sonic & SEGA All-Stars Racing, and Sonic & All-Stars Racing Transformed. He has the same name as the Japanese name for Coconuts.

Personality
Aiai is a monkey who loves bananas. He is usually absent-minded, thinking, "That banana I had was really delicious." Aiai deeply cares for his wife Meemee, his son Baby, and friend Gongon. Despite being absent-minded at times, he is very kind and very brave, going as far as exploring the inside of a volcano on his home island of Monkey Island.

Physical Appearance
Aiai has similar traits to a Spider Monkey. Although he lacks a tail, he does have an orange shirt with the letter A on it (possibly for Aiai). He has dotted eyes, a small scruff of hair, and rounded ears that stick out of his head. In Super  Monkey Ball: Touch and Roll, his look was modified. Also, In Super Monkey Ball Banana Blitz and Sega Superstar Tennis, his look was updated, giving him a blue backpack, red oval shaped cheeks, a cat-like smile, and a much sweeter look all in all.

Sonic Riders
Aiai appears in Sonic Riders as an unlockable character. Oddly enough, he is a Power-type character, and as such, pushes lighter characters around easily. However, due to his small posture, he is easily pushed around just as much.

Sega Superstars
Aiai appears in Sega Superstars with a minigame based on his own series of games where the player has to use their own body to move him around and get to the end in time, like his own games.

Sega Superstars Tennis
He reappears in Sega Superstars Tennis like other SEGA Superstars like NiGHTS and Ulala. In this game and from now on, he has his updated appearance.

Sonic & Sega All-Stars Racing
Aiai once again appears in Sonic & Sega All-Stars Racing driving a racer called the Blazing Banana which is predictably modeled after his favorite obsession: Bananas. his All-Star Move has him rolling around in his monkey ball with friends while running over anyone that gets in his way.

Sonic & All-Stars Racing Transformed
The cheeky little monkey appears in Sonic & All-Stars Racing Transformed again driving his vehicle from the previous game, but redesigned to look more like a conventional race car, like a dragster. For transformations, the car loses its wheels and sprouts banana-like structures to become a boat. Then it uses the same banana structures, but they stick from the bottom of the vehicle in a upside-down 'V' and reveals a booster to make it a jet.

McDonald's
In the 2003 set of Sonic Happy Meal McDonald's toys, SEGA included a toy starring Aiai in a Super Monkey Ball themed, banana grabbing game. He being the only non-Sonic character included in that set. This toy was also one of SEGA's free giveaways at the E3 convention in 2003.

Trivia

 * Aiai bears a resembalance to another non-Sonic character, Amigo: they are both monkeys, both of their names start with the letter A, and, they are both similar in appearance.
 * Because of Tails and Amigo not being on the box art of Sonic & All-Stars Racing Transformed, Aiai is the only non-Sonic character that is on Transformed's box art, since Sonic and Eggman are on the cover.