How do you get through the fourth gym in silver?

In Pokémon Silver, the fourth gym is located in Ecruteak City, where you face Gym Leader Morty, who specializes in Ghost-type Pokémon. To prepare, ensure you have strong Dark-type or Ghost-type moves, as they're effective against Morty's team. Defeating his Pokémon, such as Gastly and Gengar, will require careful strategy and the right type matchups. After defeating him, you'll earn the Fog Badge, allowing you to use Surf outside of battle.