Koops

Koops was a member of Mario's Party in Chill's Rescue.

Paper Chill
In Paper Chill, appears in Dry Dry Desert. Kooper notices that it is Koops his long lost cousin. Then Kooper throws Koops to Petal Meadows.

Chill's Rescue
In Chill's Rescue, Koops appears with the TTYD Party, and during the first and second-to-last encounters, sings a pie song. However, he joins Mario after they learn that they both like pie. Later, in the boss fight with Herbert, he knocks Koopa unconscious and takes over the job of being the author.

Trivia

 * Koops is the second enemy to join The Party later. The first was Ultimate Protobot in (Not So) Elite Penguin Force, and the next one would be Marylin in The Mega Snowball Fight.
 * Koops is Kooper's long lost cousin.