On cinnabar island but you need to get the secret key in Pokemon mansion first.
I think you get it in either cinnabar island gym or virdiran city gym
You battle the Snowpoint city gym leader. She has a ice Pokemon but can be defeated by empleon lvl 48+
Seven island.
After you defeat the Elite Four.
Its in viridian city
The same way as fire red!
you have to have the rainbow pass. you take the ferry
first get them on firered/leafgreen from the seven islands, then migrate them
viridian city gym. you have to beat all the other seven gyms to unlock this one.
technically there is one it is unown it looks like the alphabet.
In Sevault Canyon on Seven Island.
Velistone City