The Cocky Aliens are race of aliens who can only be defeated by being kicked 100 times (which leads to the invention of the game Shuttlecock) after which they turn into fruit (explaining the origin of pineapples, grapes, tomatoes, and watermelons).
They are enemies of the Cheetahs as they were the ones who invented Shuttlecock. In "Cheetah Castle," a Cocky Alien in a large alien suit crashed First Squad's Shuttlecock contest against the Cheetahs by abducting the Cheetahs, Commander ApeTrully, and the other First Squad members.
Using the advice of Jumpy, Lin Chung combined with the Cheetahs and destroy the Cocky Alien's suit. When the Cocky Alien sets himself to explode, Lin Chung kicked the Cocky Alien 100 times turning it into a pineapple. In "Cheetah Castle II," four Cocky Aliens later attacks Cheetah Castle and trap it in a Crystal Barrier. This time, High Roller tries to trick them to his side.
They managed to demonstrate an ability to possess humans by entering one's heads, which they did with High Roller, the Zebra Brothers, and Bearstomp. When High Roller, the Zebra Brothers, and Bearstomp are defeated, the Cocky Aliens end up possessing the other First Squad members. Lin Chung pretended to get hit in order for him to get them to leave the bodies of First Squad. Lin Chung, the Cheetah King, and Cheetah Queen then kick them 100 times and reduce them to fruits.