Monkey

Monkey is a recurring character from the Rhythm Heaven franchise, particularly Rhythm Heaven Fever.

Fan Club
In Fan Club, there are three monkeys, where one in which is the player. Per the actions you are supposed to follow in this game, the monkeys do the clapping, or otherwise "cheering."

Hole in One
In Hole in One, the Monkey is seen as one of the two main characters. It is the one on the right side of the screen tossing the golf balls at you to shoot. In Hole in One 2, the Monkey is instead female.

Tambourine
The Monkey is the leader in Tambourine. It plays the tambourine as the player must repeat them.

Monkey Watch
In Monkey Watch, there are dozens of monkeys. The player, a monkey as well, rides the watch's clock hand and "high fives" the other monkeys as the player passes by them. There is a "punk monkey" that will be followed every few monkeys, which high five off-beat.

Remix 2
In the sections of Board Meeting, instead of a woman assistant there is a small female monkey wearing glasses and a small pink dress. Instead of saying "One, two, three!" the monkey says "Oo-ookii!".

Exhibition Match
Before the last ball is thrown in Exhibition Match, The curtain in the middle of the arena rises to reveal a monkey, who is catching the pitcher's baseballs and dropping the to Slugger.

Trivia

 * Monkeys made a cameo in WarioWare: Smooth Moves and Game & Wario, by the same creators who made the WarioWare series.
 * The first monkey appearence in the series is Showtime in Rhythm Tengoku.