The final gym is the Viridian City Gym. Blue is the Gym leader.
Not enough info: which gym leader?
Janine I think
The eighth gym leader still awaits, as well as the whole of Kanto.
defeat all the other gym leaders
You beat the 6th gym leader.
he is Brock. hes in pewter city.
It's right next to the dojo in Saffron City
Viridian gym i forgot his name the team rocket boss guy.
actually there isn't 9 gym leader there is only 8 like the other ones. Actually, the 9th gym leader in heartgold and soulsilver would be the first gym leader in Kanto after you beat the elite four the first time, you can face the kanto gym leaders in any order.
Blue (The eighth gym leader) is waiting on Cinnabar. He won't battle you unless you've beat the rest of the gym leaders
His name is Blue, and he is on Cinnabar Island. Show him the other 7 Kanto Badges and he will go to the Viridian City gym. Then, go to Viridian City and battle him at that gym.
The SS Anne is not in HeartGold or SoulSilver however when you arrive in Kanto you'll arrive in Vermilion City so you go and challenge the Gym Leader there.