After you beat the 15th Gym leader, you have to go to Cinnabar Island then you talk to Blue who is the only person on the island then he tells you to go the the Gym in Viridian City, where you battle him after getting through the maze.
The fourth gym leader in Pokemon Soul Silver is in Ecruteak City.
in his gym
the 16th gym leader is:Trainer Blue
He is on Cinnabarr Island.
go to the Pokemon gym
you dont
the 15th gym leader in soul sliver is blaine and he uses only fire type pokemon
Ghost Pokemon.
Blue, the last gym leader in kanto region
The last gym is in viridian city
Morty is the Gym Leader of the Ecruteak City Pokemon Gym.
The Gym and Gym leader is in the bottom left of the city near the Pokemon center.