You need the Rainbow Pass
After giving the ruby to Celio, he will give you a rainbow pass then you can go to 4-6 island.
After you defete the Eliete 4 you can get to islands 4, 5 , and 6
you have to go to island 4 5 6 7 8 or 9
You have to beat the Cinabar Island gym leader Blaine to get a ferry to the Islands
If you defeated the Elite Four then if you have 60 Pokemon go to 1 island then talk the guy on the machine he will tell that you need him a RUBY stone it will be at the Mt. Ember then there is a two rocket grunt you will need rock smash to get through
you have to beat the elite 4 before you can get the pass to the islands.
== == when you got to 4 5 6 7 AND SO ON Island Ill tell ye'!
4, 5, and 6 island
4 -5 6 -6 6 5 4 -5 6 -6 6 4 -5 6 -6 6 5 5 -5 5 4 4 7 -7 -6 6 -7 6 -6 -5 6 7 -7 -6 6 -7 7 -7 -6 6 -7 6 -6 -5 6 5 -5 5 4 4 4 -5 6 -6 6 5 4 -5 6 -6 6 4 -5 6 -6 6 5 5 -5 5 4 4
5-6 gb
6*4/5 = 24/5 = 44/5 or 4.8
When you get the National Pokedex you can go to islands 4, 5, 6, 7, and the two event islands 8 and 9. Get the Ruby and the Sapphire from islands 1 and 6 and give them to Celio. Then you will have access to the Cerulean Cave where you catch Mewtwo!