Here is the full list of all 12 Monkey Party achievements.
Drop your first gibbon!
Combine your first Capuchin!
Combine your first Bonnet Macaque!
Combine your first Barbary Macaque!
Combine your first White Cheeked Gibbon!
Combine your first Chimpanzee!
Combine your first Baboon!
Combine your first Japanese Macaque!
Combine your first Orangutan!
Combine your first Ponginae!
Combine your first Gorilla!
Have two gorillas on the screen!