I agree firestorm is OP, but there's a simple solution built in. You have the dumb jock that can't grasp basic chemistry in control, and the super nerd in his head with some sort of communication difficulty (they argue, he can't explain well, he gets frustrated, whateverthefuck) so he can't do much very often. Likely takes the name because he can do fire well. bam, done.
I'd also like to point out that Firestorm is easily one of the nerdier characters in all of DC. If they can pull him off to the not-comic-biased audience, we may have a DC coup incoming in the next 5 years. Marvel broke pop cultures' hymen, DC's gonna creampie it. And if we're all lucky, and good little boys and girls, Image will do anal in the next 20 years.