The details of Waluigi's past are unclear since he has no confirmed back story although, he has evidently been antagonizing the Mario Bros., especially Luigi, for quite some time before his debut as seen in the opening of Mario Tennis where he and Luigi confront each other.
Waluigi is the same age as Luigi. He is also his arch-nemesis as Wario is to Mario. Waluigi has been rumored to be Wario's brother due to their similar appearance, but conflicting sources both support and reject this notion.Even Charles Martinet does not know whether Wario and Waluigi are brothers, but he personally thinks of them as "just two nice, evil guys who found each other." Waluigi also runs a motor oil company. Waluigi can be contacted via the following address: Waluigi, 26 Grimace Lane, Mushroom Kingdom, IMG EEK. The last part, which mimics British postal coding, is a pun of "I'm geek."