To get to Blaine, he is on cinnabar, but the last gym leader... He is in one of the towns once you defeat Blaine, I think it was Viridian or Vermillion. =)
The gym is in Blackthorn City.The gym leader is Clair.
You face them after you beat the eight gym leader
Red is in mt.silver and blue is the eight kanto gym leader
In Pokémon HeartGold, you can find the 3rd Gym Leader in Goldenrod City.
no you can not become a gym leader in any game.
Gym Leader Blue
The 14 gym leader in heart gold is in Saffron City.
the 16 leader is in virdinian city after beating every other gym leader
You CAN NOT become a Gym Leader in Pokemon HeartGold and SoulSilver or ANY MAIN SERIES POKEMON GAME.
Go to Blackthorn city. The gym is there
try beating the gym leader
Obtain it from a gym leader.