it is in goldenrod city after azela town
the third gym is in goldenrod city right after ilex forest
you have to break the code
Goldenrod city, you battle Whitney and her evil mootank.
the third gym's HM is Strength. Receive from the Hiker who comes out of Mt. Mortar on Route 42
You get the third badge in sapphire when you get to Mauville. You have to battle Gym Leader Wattson in the Mauville City Gym.
your a fag.
On pokemon Heart Gold and Soul Silver you can battle him if you got the another 7 gym badges then go to Viridian city and go to his gym then battle him
In order to battle the third Gym Leader Korrina in Pokémon X and Y, you must first battle all the trainers inside the Gym. Then you'll be able to rail over there with your rollerskates.
After you beat the gym, you must leave, heal ur pokemon, then go back and talk to the leader and she should give you the badge
Beat Maylene then, Wake. (Crasher Wake). Then,go to Celestic town. Then, battle her.
You can't. There is no way in Pokemon Gold, Silver, or Crystal to re-battle the gym leaders. The only Pokemon game that I've seen this in is the 3rd gen games (RSE).
The third gym leader is in Hearthome City. But i think the gym leader says that you are not ready yet. (don't remember) you have to beat Pastoria and Veilstone's Gym leader first and then you can battle Hearthome's leader.