Wade Wilson is the legendary Merc with a Mouth known to most as Deadpool. He is a champion when it comes to breaking the fourth wall.
LOTM: Darkness Incarnate
Deadpool tagged along with Angewomon, Lizbeth and Maka after they fought him during the Nod attack on New York. He proved to be helpful to them, but he also proved to be a big pain in the ass.
A League Storyline
Deadpool was watching TV in his apartment when he is suddenly summoned by Samael (although he doesn't know who he is at the time) and is tasked with killing Frankie. While hesitant to do so at first, he immediately jumps on board when Samael promises $5,000,000 in cash along with a lifetime subscription to Cosmopolitan Magazine and chimichangas.
Deadpool is sent to the Southern Air Temple where he confronts Frankie, Aang, Katara, Sokka, Iroh, and Zuko. He easily defeats them all and is just about to kill Aang when Frankie, under the assumption that he was killed from being impaled by Deadpool, is brought back by Aria and becomes a False Super Saiyan. He then proceeds to beat up on the mercenary until the transformation wears off. When Deadpool is about to kill him off, Frankie promises that he will be paid by a literal goddess if he joins up with them. Deadpool agrees and he joins the team on their adventures.
LOTM: The Angels Return
Deadpool had been hunting down Metal Face, who had been causing trouble in the Marvel universe. He finally tracked the metal chatterbox down to the Mighty Orbots universe...and killed him, saving the Disney Angels and their pals. He also seems to have taken a liking to Mervamon.
Angewomon is grateful for Deadpool's help and is pleased to have him, but Oswald does not seem excited at all.