The fourth Gym Leader in SoulSilver is the Ghost Pokemon trainer Morty in Ecruteak City.
He will give the Fog Badge when you beat him, as well as TM30 (Shadow Ball) and the ability to use Surf outside of battle.
Morty will have the following Pokemon:
Gastly lvl. 21
Haunter lvl. 21
Haunter lvl. 23
Gengar lvl. 25
The gym will be locked when you first get to Ecruteak, you first have to speak to Morty inside the Burnt tower, then go down and make Entei, Raikou and Suicune run away. He'll then go back to his Gym.
you can't get to any of the Sevi island in Pokemon Heartgold and soul silver
With your pokemon... noob
get their numbers
In the gym!
beat the all the gym leaders
fighting dojo
The fourth gym leader in Pokemon Soul Silver is in Ecruteak City.
He has ghost Pokemon that put you asleep. It is extremely annoying!
2 haunters a gastly and a gengar
You're done with the game.
beat the elite four.
I don't think you can :P