Oolong is a shapeshifting pig, although he was expelled from shapeshifting training and lacks the ability to change his form for more than five minutes at a time without a break. (Dragon Ball's other shapeshifter, Puar, completed the training and does not have this limitation.)

Oolong's initial appearance was as a villain who terrorized a village and kidnapped their young women. Unfortunately for him, the young women were quite comfortable being stolen and living in wealth and he never found the "nice shy girl" he was looking for. Son Goku defeated Oolong and the girls were returned to their village. Bulma decided that he might be useful on her dragonball quest and persuaded him to join their expedition. He does have his moments. In Emperor Pilaf Saga, Oolong realize that the one wish to the dragon is enough to stop Emperor Pilaf's plan as the dragon can only grant one wish. In the manga and the original Japanese anime, Oolong asks for a pair of female underwear just before Pilaf make his own and ruins Pilaf's plan. In the English anime, Oolong asks for the most comfortable underwear in the word, but inadvertently gets female underwear. For a time, he waers them on his head.

After Dragon Ball, Oolong was kept around primarily for comic relief. His poor shapeshifting skills (and innate cowardice) made him a very weak character that didn't have much to do once the tone was shifted to more serious action.

Like Muten Roshi he is also a pervert, but the difference between them is Oolong is not as big of a pervert as Roshi is. Oolong is also a coward preferring to run away in the middle of a fight.