Yes, but Kanto in GSC/HGSS is lackluster as fuck. It is not the same as playing through the region in RB/FRLG.
4 consecutive generations of Kanto, man. There's no need to remake it again. Come on, now. I first noticed what Wiseblade pointed out when I was on Bulbapedia looking for E4 info and found that Bruno had sprites for four different generations (RB, GS, FRLG, HGSS).