Flatman is one of the founding members of the Great Lakes Avengers and second-in-command under Mr. Immortal. He, alongside Doorman, has proven himself to be a good recruiter, signing up the Grasshopper, Squirrel Girl and her partner Monkey Joe.
Flatman was approached by Avengers attorney, Connie Ferrari, with an offer to make the GLA an official branch of the Avengers. The catch would be that the team would have to move from Milwaukee to Detroit, but they would be given a Stark Holdings warehouse to use as a headquarters. Flatman put out a call to all the most recent team members to meet at the local coffee house. Big Bertha and Doorman answered, Squirrel Girl had another team, and Mr. Immortal had himself buried after his latest drunken bender so he could have some time to think on what he wanted out of his life. While it took awhile for the team to come together, it eventually did and may have gained a new member in Good Boy.
Flatman has the mutant ability to stretch any part of his body to great lengths and possesses a flat, nearly two-dimensional body. He uses his flatness to help dodge attacks like thrown shurikens, slip through very thin spaces like under doors and appear invisible by turning to just the right angle. He uses his elasticity to help "launch" attacks like slingshotting rubber ducks into orbit.
Flatman possesses extensive knowledge of fashion, which he was reported to have "studied in college." He is able to identify a women's shoe and describe it in detail.
Flatman is also adept at accounting, and has even itemized all of Deadpool's outrageous expenses during his brief stay as a reserve member of the Great Lakes Initiative.
Flatman's mutant powers can attribute his mastery of the deadliest martial arts fighting form of all... Origami-Fu! Deadpool can attest to this, as he has experienced first hand Flatman's crane, monkey, tiger, and frog styles.
Flatman has proven himself to be an excellent poker player. He and his teammates were invited to the first annual Superheroes' Poker Tournament. In the end, Flatman becomes tournament champion by defeating Thing's four fours with a straight-flush.
In Other Media
Fantastic Four (2006)
He appears in the episode The Cure, as Thing's rock like mutation has been "cured" the Fantastic Four hold auditioning for potential recruits. Flatman auditions, but is dismissed by Reed Richards as they have similar powers, with Reed being far superior in power strengths and levels.
The Superhero Squad Show (2010)
Flatman appears in the "Cometh the Iceman" as a teacher for the Squaddies, even though most of the information he tells them is wrong. He is portrayed as extremely boring and monotone. He uses Reptil as his assistant but dismisses anything he says as incorrect.