In the beginning of the game, he isn't there. Towards the end, you will find his rival on cinnabar island by himself. After you talk to the rival, he leaves to go back to viridian. Fight the cinnabar gym leader, go back to viridian and the gym leader should be there. The man you talk to on Cinnabar Island Isn't the gym leader, but his rival. After you speak with his rival on cinnabar, the gym leader reappears in viridian. You have to fight and beat the cinnabar gym leader first.
Brutus
The leader Black List is Ghost rival to Sir Alex Roy
Chattrapati Shivaji Maharaj
There goes the leader of our rival gang. We must outwork our rival gang.
Megatron
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.
Leon Trotski was a Russian leader a century ago. He was a rival of Lenin.
Bonecrusher
bianca vs electric gym leader
The seventh time around, you battle your rival at the Dragon's Den in a double battle with you and your rival against Lance, the Champion, and Clair, the eighth gym leader. View the Related Link for more information.
After to defeat Flannery [Lavaridge GYM Leader] your rival Brendon/May will give it to you.