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
== == when you got to 4 5 6 7 AND SO ON Island Ill tell ye'!
you have to beat the elite 4 before you can get the pass to the islands.
4, 5, and 6 island
5-6 gb
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
no.1 cut no.2 fly no.3 surf no.4 strength no.5 flash no.6 rocksmash no.7 waterfall
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!