Bouncing Boy was a member of the Legion of Super-Heroes in the 31st Century, whose main power was his spherical body and his ability to bounce.
Pre-Zero Hour History
Bouncing Boy was among the team of Legionaires who summoned Supergirl from 1962 to the future to stop Positive Man, who they had all failed to stop. While she dealt with that threat, he was incapacitated by the Chameleon Men. Supergirl later revived him once she had defeated them. ("Supergirl's Greatest Challenge!")