The 16th gym leader is Blue. You can only fight him after you win all 15 gym badges. after you get all 15, go to cinnabar island, blue will be there. show him your badges and he will return to the gym so you can fight him
there is no 16th gym in soulsilver u dope....
You CAN NOT become a Gym Leader in Pokemon HeartGold and SoulSilver or ANY MAIN SERIES POKEMON GAME.
Well after you defeat 15 gym leaders in Pokemon HeartGold / SoulSilver go to Cinnabar Island and talk to Blue.
the 16th gym leader is:Trainer Blue
yes, and you have to battle her to get your 16th gym badge
After beating the 16th Gym leader, you can Catch Mewtwo, and then just train for Red.
Not enough info: which gym leader?
In the goldenrod gym.
After you beat Blue, the 16th gym leader
Brock.
beat gym leader
Sabrina