Philosophía
"The devil made me do it"
1. wonder woman - Funnily enough, he'd take almost every fight -- if not for the lasso. That's something he can't escape due to intangibility, since it ensnares souls and such. Remove the lasso, and he'd eventually put her down with energy projection/intangibility. The lasso is essentially a 10/10 for Diana assuming it works and it's not just a glorified rope while without it FS'd probably beat her 10/10, which is kind of funny.
2. j'onn - a much harder match-up for him. J'onn can probably take him with TP in almost every match that does not involve fire [and also depends on how effective it would be]. I'd say J'onn 7/10 at least.
3. hal - I'd say Hal pretty much all matches. He has a counter for everything.
4. shazam/billy - Hm, this is pretty interesting. Lightning/magic would be pretty decisive in countering intangibility and speed to do so before he manages to do it. It has affected Deadman. But if that wouldn't work, it'd just be a matter of fs hitting him until he falls. it wouldn't be the first time firestorm beats a marvel character heh.
5. supergirl - can he make kryptonite? assuming he can get off intangibility, supergirl can go intangible, too [it's harder and very unlikely, so eh] Assuming he manages to go intangible and she doesn't blitz him, he'd be able to spam red sun/kryptonite/bombs for the KO. But that pesky speed as always is a deal breaker imo. Supergirl doesn't have the HV/Speed/Voice etc. raw power and versatility of her cousin [i.e. he can use them to counter .. everything] which makes her a bit of an underdog otherwise. She's closer to Gladiator or Power Girl in terms of versatility which is...not good to be against Firestorm.
6. orion - ronnie has outperformed him pretty badly when they met. the motherbox and astro force should be able to pull something here theoretically, but it's very feasible ronnie could take him.