I never considered Ratt a hair band, but rather one of many established bands that adopted the look when it became the big thing in around 1986 or so. Hell, even Priest adopted the look during the Turbo era, but they were in no way a hair band.
To me, the actual hair bands were the ones that were signed in the record industry frenzy after Motley Crue blew up with Home Sweet Home. That song and video defined the formula that became hair metal- big hair, makeup, spandex, and the power ballad to attract females to the band. We used to refer to them as Poser Bands.