Go to Vermillion city and go to the pier where the SS anne was. There will be a boat and a man asks you wich island you want to go on. 1, 2 or 3.
Go to Vermilion City and go to where the S.S. Anne was
go to One Island
beat the elite four then go back to island one and talk to Celio in the Pokemon Center
One island.
The island is called Four Island, you can take a ferry from Vermilion city/any other island after beating the Elite Four and visiting Celio on One Island.
talk to Celio on One Island
When you get your natrional dex and get the ruby from 1 island and give it to Bill's friend. One of the Elite Four will be at 6 island and the boy [ it's auctully a boy] will be blocking the doorway to the Elite Four.
You have to beat the elite four first and go to the sailor in vermilion city and go to one island for the rainbow pass from bill. then you can go to four island and the rest with the rainbow pass.
Go to one island and talk to him.
you have to beat the elite four to get to four island. talk to celio after beating the elite four. he will ask you to find him a ruby. the ruby is located on 1 island in mount ember. find it and give it to celio. then, he will give you the rainbow pass, which allows you to go to four, five, six, and seven island.
After you defeat the Elite Four.
Deoxy IS IN ISLAND 9 AFTER YOU BEAT THE ELITE FOUR
get her in icefall cave