If you are talking about Heartgold, and Soulsilver, and in Kanto, then in order to wake the SNORLAX in front of the tunnel, you use the Pokeflute, which you can get to by tuning in your pokegear radio to the very top.
The fourth gym leader is Erika, the Grass trainer.
You have to Dive and then you can battle the Gym Leader.
The fourth gym is in Lavaridge the 6th is in fortree.
The fourth gym leader is Flannery.
In Gold the fourth gym Leader is Morty. Morty specializes in Ghost type pokemon, and his gym is located in Ecruteak city.
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The fourth gym leader hates ghost type pokemon. ex:Gastly
The fourth gym leader is Maylene in Veilstone City, a fighting type gym leader.
The fourth gym is in Ecruteak City. It is a ghost type gym and the leader is named Morty.
The fourth gym at Pokemon fire red is grass type gym
just beat the fourth gym leader
You battle the fourth gym leader.