Although his powers are never explicitly stated, it could be extrapolated that he had fire-based abilities due to his name and logo. He may also be able to fly due to the woman onlooker mistaking Syndrome (who was flying at the time) for Fironic. This is corroborated by the LEGO The Incredibles game, which gives him the power to fly as well as to shoot fire from his hands.
Near the end of the first film, a woman mistook Syndrome (who had just saved her and others from being crushed by a tanker truck which the Omnidroid v.10 had thrown at them) for Fironic, though another onlooker promptly reminds her that Fironic had a different outfit.
The first on-screen appearance of Fironic was in a flashback, showing that he and Gazerbeam had personal connections with the father of Winston Deavor and Evelyn Deavor. However, this relationship ended when superheroes were made illegal and they were forced to go into hiding.
