Monkey D. Luffy is the main protagonist of Eiichiro Oda's One Piece series, and he set out to sea with the aim of becoming the King of the Pirates. Having eaten the Gum-Gum Fruit, Luffy's battle prowess has grown tremendously and with more training, he's become one of the strongest in the series.
Source:https://www.cbr.com/one-piece-every-time-luffy-been-defeated/