Instructions
Find the Rocket Game Corner in Celadon City. Find the team rocket member and fight him. Walk to the poster and press ̶0;A,̶1; which opens up stairs on the right. Travel to the fourth basement floor and fight Giovanni. After you beat him, he will drop the Ghostbuster.
Find Johto in Saffron City. He knows how to fix the Ghostbuster. Travel to Sliph & Co and go upstairs. Fight the guard at the top level and go inside the room he is guarding. Fight Jess and Jamie and talk to the manager, who will tell you that Morty in Johto knows how to fix the Ghostbuster. He is the Ecruteak Gym Leader .
Travel from Vermillion Olivine by boat. Travel to Ecruteak. Morty is not at the gym, but is instead at a burned tower where you released dogs earlier in the game. You must defeat Morty in battle before he will fix the Ghostbuster.
Travel to Cerulean. Fight Carlos and defeat him.
Use the Ghostbuster. This will let you get past the ghost blocking the path. Otherwise, you cannot see the ghost or do anything to stop it. The ghost is an Lv42 Haunter. You can attempt to catch the haunter.