Bubbles

Bubbles lives on King Kai's small planet, which has gravity ten times stronger than Earth's. This enhanced gravity makes the seemingly simple task of catching Bubbles an exhausting challenge, since the monkey is perfectly adapted to the heavy conditions while visiting trainees are not. When Goku arrived to train under King Kai before the Saiyan invasion, catching Bubbles was the first challenge assigned to him. Only after mastering movement in the heavy gravity by successfully chasing down the monkey was Goku allowed to proceed to the next stage of training with Gregory.

Despite his role as a training tool, Bubbles is very much a character in his own right. He is playful, mischievous, and clearly enjoys the chase, treating each new trainee as a source of entertainment. He shares a close bond with King Kai, often seen lounging alongside him during quieter moments on the small planet. Their relationship is one of comfortable companionship, providing King Kai with company during the long stretches between visitors.

Bubbles met his end alongside King Kai and Gregory when Goku used Instant Transmission to teleport the self-destructing Cell to King Kai's planet, killing everyone there in the explosion. All three were later seen in the afterlife still together on the small planet, their dynamic unchanged by death. Bubbles continued to appear in the Other World throughout Dragon Ball Z and into Dragon Ball Super, a constant and comforting presence in King Kai's corner of the afterlife.