It's in Azalea town, and the leader is Bugsy, and he has bug pokemon, so be sure to bring lotsa grass types and dark types. And then also teach them all fire type moves, and give them each a masterball. Only then can you win.
The third gym leader is Whitney.
The final gym is the Viridian City Gym. Blue is the Gym leader.
Gym Leader Blue
Not enough info: which gym leader?
You CAN NOT become a Gym Leader in Pokemon HeartGold and SoulSilver or ANY MAIN SERIES POKEMON GAME.
first it's not your rival and second the gym leader blue can be found on cinnabar island if you have all the other badges talk to him.
In the goldenrod gym.
Brock.
beat gym leader
in blackthorn city.
Catch the 2 Farfetched in the Ilex forest for the one worker.Umm if i recall correctly after you beat the second Gym leader and team rocket this old guy gives it to you, but im not sure, but you do have to beat the second gym leader for sure.
The eighth gym leader still awaits, as well as the whole of Kanto.