You will need have beaten Blaine on Cinnabar Island to gain access to Island One. When you exit the Gym, Bill will ask a favour and take you to Island One.
he isn't in the one island
one island
do the errand for bill on one island.
One Island.
get laid
One island :)
Take the ferry from Vermilion City/Island One/any other island.
Give it to Celio on one island.
at the top of mt ember, island one
he is in one island in the hospital.
One island in the north.
You get a map from Celio, on one island.