The original Legion of Substitute Heroes was a five-member team: Chlorophyll Kid, Fire Lad, Night Girl, Stone Boy, and Polar Boy, who conceived the idea of the Substitutes and served as team leader. All were Legion hopefuls who had tried out for the Legion, but were rejected due to their powers being considered too limited or otherwise inadequate.
The Subs get off to an uneven start and are often the butt of jokes and humorous storylines, but eventually prove their worth to the Legion on several occasions. Stone Boy is later offered a chance at full Legion membership, but declines in order to remain with his friends in the Subs. Regular Legionnaires Dream Girl and Star Boy later join for a short period, after Star Boy's temporary expulsion from the Legion. Other legion rejects like Color Kid, Infectious Lass, Porcupine Pete, Double Header, and Antennae Lad all become later members of the Subs.
Polar Boy eventually disbands the Subs and becomes a full-fledged Legionnaire. He becomes a well-respected member of the team and is eventually elected Legion Leader. During this time, Cosmic Boy forms a new group of Substitute Heroes that are available to assist the LOSH when needed. This team consists of Cosmic Boy, Bouncing Boy, Duo Damsel, Night Girl, Comet Queen, and the second Karate Kid.
In the alternate timeline commonly referred to as "Five Years Later" Night Girl is married to her long term beau Cosmic Boy and they have a child. Fire Lad, Chlorophyll Kid, Stone Boy, Infectious Lass, Color Kid, and Porcupine Pete all join with the second Invisible Kid, Tyroc, and Ron-Karr in the resistance movement to free Earth from the control of the Dominators. After Earth is freed, Fire Lad, Stone Boy, Color Kid, Chlorophyll Kid and Porcupine Pete serve in the United Planets militia. Polar Boy forms his own team of heroes based on Tartarus, while Night Girl and Infectious Lass live at the Legion's headquarters on Talus.
More recently a new team of Subs was shown consisting of Rainbow Girl, Stone Boy, Fire Lad and Chlorophyll Kid. This team helps the Legion in defeating Earth-Man and his Justice League of Earth.
A version of the team appeared on an episode of The Legion of Super Heroes animated series. This version had original members Chlorophyll Kid and Stone Boy, but instead of the other founders it used Infectious Lass, Color Kid and Porcupine Pete.