Kid is a young golfer from the Mario Golf titles. He debuted in Mario Golf for the Game Boy Color, as one of the four characters players could choose from the beginning. He could be uploaded to the Nintendo 64 Mario Golf for training, and he also went on to appear in Mario Golf: Advance Tour. In Mobile Golf, he was an unlockable character. Kid appears as a Support Spirit in Super Smash Bros. Ultimate.
He apparently started playing golf ever since the age of three and had already become a golfing prodigy at age ten. In Mario Golf: Advance Tour, it is established that Kid had become the Grand Champion in the last game. However, he was injured badly due to excessive training caused by strain of the muscles and joints to the point where he could not even grasp a golf club. It was said he could no longer golf and lost his title to the former champion, Gene. After a five year recovery, Kid became an avid golf trainer to Neil, Ella, Buzz and Helen, until the Club Manager influenced him to pick up the club again when he signed them up in Marion. He ascended the ranks quickly and took back the championship.
Kid lead the title over the Links tourney. He also ended up forming a doubles team with Gene to advance up the doubles (more likely for the benefit of Gene gaining another title).
Kid never seems to lose his cool, and always tries to be fair to his friends and his foes. He encourages his students to keep going strong, no matter what. He is a very respected golfer and is considered to be just as good, maybe even better, than Mario.