Flea does a have a very powerful, independent style - he merged traditional rock, slap, and punk styles into something that's very common today but was pretty unique in the early days of the Chilis. And he was commercially successful enough that this mix got heard and influenced a whole new generation. He's not my favorite player, but I would definitely put him in my top 10 list of most influential bassists...
It's well known and has been discussed here in the past that Flea was also an Alembic user. Somebody will follow up with the specifics, but he was the cover guest of an issue of Bass Player during the Chili's peak days and in his interview, he mentioned that he used an Alembic in the studio on at least one of their huge album hits (I think it was either Mother's Milk or Blood Sugar Sex Magik). He was very visible onstage and in ads at that time with Musicman, probably their most high-profile endorser, but in the studio he choose a solidbody Alembic (I think an Epic, but I'm not sure). His change to endorsing Modulus didn't happen until a few years later (that must have been around 1994 or so), so I'm not quite sure what happened.
You definitely can hear different sorts of bass sounds on the Chili's records, some very distinctively the Stingray, some definitely not although I wouldn't have picked Alembic as those alternate sounds.
David Fung