ok now listen you need to get the ruby and sapphire and give it to bills freind that's working on the PC on one island.
You have to beat the Elite Four once.
get her in icefall cave
You must beat the elite four first, then you can enter.
You have to beat the elite four and complete your pokedex.
I think by beating the Elite Four
Beat the elite four.
try the ice cave on four island. (you have to beat the elite four first)
beat the elite four 12 times and you will find her in the cerealian cave
U have to beat the elite four and get the nation dex
You will gain access once you have beaten the elite four
in leafgreen the elite four because i have evolved mine there and creuluen cave in leafgreen. and in emerald sky pillar and the elite four hoped that helped! -Drew
first you have to defeat the elite four and the champion.then you can go freely to the cerulean cave