cinnabar island, you moron. haven't you checked the map? i know where it is without looking at the map, that's how good i am.
Blaine's Gym is in Mahogany Town.
Go to seafoam islands, and climb the latter.
You explore the mansion until you come to a room with two houseplants. There'll be a pokeball there. Pick it up. It's the key.
up the stairs in seafoam island
bottom floor of Pokemon Mansion
Head over to Seafoam islands where Articuno is located.
Go to Blaines gym underneath there is a series of floors which lead to Articuno
Blaines Gym now resides in the sea foam islands when you enter the islands take the ladder and you'll be in his gym.
They are in these cities. Pewter,Cerulean,Vermilion,Fuscha,Saffron,Celedon,& Viridian. Blaines gym is at the seaform islands.
You need to acquire the Secret Key that can be found in the basement of the Pokémon Mansion and then you can use the Secret Key to enter into Blaine's Gym.
Although i have not played the new version of gold and silver, he was on cinibar island on the old games. the real cinibar island though, not blaines secret gym
You have to go to Veilstone City and go to the gym. Then you battle gym trainers and go past them. You will get to Maylene, the third gym leader. You can battle her. Unless you're talking about the Hearthome Gym. Fantina is the leader of that gym. If that's what you meant, you need to fight the Veilstone Gym and the Pastoria Gym first.