The key is in the Pokemon mansion.
It unlock the door to the gym in Viridian City. .
You will need to use the Secret Key which is hidden in the basement of Pokemon Mansion which is located on Cinnibar Island.
in the mansion.
That is easy. You have to go to the Pokemon mansion and find the key to unlock the gym.
On cinnibar island.
there would be a ouiz in each space answer it and the door will open get it wrong a face the guy in center
its actually the 8th gym so you need 7 badges and then it will unlock
Cinnabar Island. To enter you have to find a key in the mansion nearby.
seventh badge is cinnabar island. Fly to Pallet Town, surf south. Then go into pokemon mansion and find the secret key to unlock the gym
You have to find the key in the abandoned mansion.
go to pallet town and swim down to cinabar island and get the key in the mansion and go the gym and unlock the door and there you go
Beat the seventh gymleader and when you come out of the gym a guy will give it to you