i cant explain
The 6th gym leader is in Fortree City.
The 6th gym leader is in Canalave City.
The 7th gym leader in Pokemon yellow is in Cinnebar Island, which is south of Pallet Town. You need a Pokemon with Surf to get there.
The 6th Gym Leader in Pearl is Byron who is in Canalave City.
Brock is the first gym leader in pewter city.
Giovanni
The 6th gym is in Saffron City the gym leader is Sabrina she uses Psychic type pokemon.
The 6th gym leader in Pokémon Sapphire is found at the Fortree Gym. The name of the gym leader here is Winona.
celadon city
The 7th gym leader is Blaine. He the gym leader of Cinnabar Island gym. He uses Fire type Pokemon and he will give you the TM that contains Fire Blast when you defeat him.
steel
Byron