Grunge WAS started by bands like Malufunkshun, Mother Love Bone, Skin Yard, The Melvins, Green River. Mark Arm, Jeff Ament, Stone Gossard, Andy Wood, Chad Channing are many names of whom started the bands around mid 80s.
Mudhoney, Soundgarden, MLB, Sonic Youth began to record albums which caused a diversion between the hair bands of Bon Jovi etc. - Soundgarden led the charge and suddenly in 1989, Andy Wood was dead. This then brought Temple Of the Dog to the front, Soundgarden, Nirvana and Alice In Chains recorded more succesful albums and then from on it went on and on..
Pearl Jam can be categorized as a grunge band, members before PJ were in totd, green river, mlb, fastbacks...
Members collaborated with other grunge music counterparts during pj's reign and their sound is *******ly grunge, most *******ly on the first two albums.
That's the funny thing about memory, we are not what we think ourselves of, we are what people say we are.