when you are at cinnabar island keep on going east until you see a tiny island with a girl near it (picnicker) and go up the the ladder.
its in seafoam island not cinnabar
On Pokemon soul silver the cinnabar gym is located inside Seafoam Islands.
you walk right in the cave island
Cinnabar Island.
meet blue, the gymleader on cinnabar island
Go east of Cinnabar Island to the Seafoam Islands.
you have to have 7 kanto gym badges then find blue at cinnabar island
Go to Cinnabar island and talk to Blue. He'll agree to go back to his gym and battle you.
Well after you defeat 15 gym leaders in Pokemon HeartGold / SoulSilver go to Cinnabar Island and talk to Blue.
first it's not your rival and second the gym leader blue can be found on cinnabar island if you have all the other badges talk to him.
Blue (The eighth gym leader) is waiting on Cinnabar. He won't battle you unless you've beat the rest of the gym leaders
go to cinnabar city you'll see somebody talk to him he'll tell you He's the gym leader for virdian city you will see him at the gym after that