You must give the Ruby to Celio to get the Rainbow Pass, allowing you to get to 4th-7th island.
inside the rocket warehouse on the fifth island.
Growlithe is found in the Pokemon Mansion on Cinnabar Island in Pokemon Firered.
on cinnabar island
Beat the pokemon league.
There no Mew in firered.
you can get deoxys at birth island
in 1 island Pokemon center
On Cinnabar Island
Deoxys
no
On Birth Island
There is no island 9.