There's none, unless you mean the statue that opens and closes the gray walls. You just go up to the Mew statue and press 'A'. There should be a reachable one on every floor.
You will need to work your way to the basement in the Pokemon Mansion, you will then find the Key.
The Pokemon Mansion is at the top of Cinnabar Island near the Gym. There you can catch any fire types like Vulpix. You can also find Muk and Grimer.
Eevee can be found on the roof of the Pokemon Mansion in Celadon City. You have to go around and use the back entrance, though, to get to the room where you find it.
Within the Cinnibar Mansion. You'll find Muk and Ditto here, so bring some Poke Balls, too.
Go to pallet town and then you use surf in under prof oak house.
i think that it is in the Pokemon mansion
You have to find the key in the abandoned mansion.
If by vixen, you mean Vulpix, then you can find it in the Pokemon Mansion on Cinebar Island. Otherwise I have no idea.
You will need to work your way to the basement in the Pokemon Mansion, you will then find the Key.
You will find the key to the Gym of Cinnabar Island, From the Pokemon Mansion that is on the same island.
Articuno is somewhere in seafoam islands.you can find it in the seafoam islands from fuchisia NOT the island with POKEMON mansion
you can find it in cinnabar's destroyed mansion. Also there are high level ditto's in cerulean cave.
You have to go into the pokemon mansion, find your way through it, and pull a switch and the gym will open.
in the Pokemon mansion every one says you need leafgreen to find vulpix but you can find nintales even better than vulpix!
The secret key is hidden in the basement of Pokemon Mansion which is located on Cinnibar Island.
Go into the Pokemon mansion and look around. At the end you will find the key to the door.
Pokemon mansion floors: 1f, 2f, 3f & B1 also on routes 7&8you have to trade from firered