Pokémon Gold and Silver/The Magnet Train

To get the magnet train pass, go to Saffron City and there will be a building south of the train station, go in it and talk to the woman at the table, now go upstairs and talk to Copycat. Now go to Vermilion Pokémon Fan Club and talk to the boy on the left, he'll give you the doll, now give it to Copycat and she'll give you the rail pass. Now the underground is open where you can get some good items