What about the "Archies"? They were the biggest act, even though they didn't really exist--but the music was bubblegum, by any standard. It was certainly called "Bubblegum" at the time(I was a DJ back then, and I remember it all too well--There was a lot of acrimony, at the time, toward music that wasn't "heavy", which is probably has more to do with the reason that the people who played it disliked it--it was not cool to play that kind of stuff at all--Musicians, to be taken seriously, had to be "counterculture"--this was "teeny bopper" music, and totally uncool to listen to, let alone play.

One thing that you've missed, musically, is the "Tom Tom" bass line--it was a straight eight, like the cliche Indian tom toms in the TV and Movie Westerns--and was a break away from the syncopated "Hully Gully" beat that had been at the bottom of all the teenybopper dance music from the middle sixties--