you can't it's impossible.
You CAN NOT become a Gym Leader in Pokemon HeartGold and SoulSilver or ANY MAIN SERIES POKEMON GAME.
Not enough info: which gym leader?
In the goldenrod gym.
Nope i dont think that would ever be possible lol
Brock.
beat gym leader
Jeff Gordon
in seafoam island
defeat gym leader.
He is the Gym Leader in Cinawood.
in blackthorn city
Simply beat the gym leader in every gym.