You have to have beaten the Elite Four and sailed to Kanto. After making it to Saffron City, you should hear that copycat has lost one of her dolls. Go to Vermillion City and into the Fan Club and talk to the guy with the Clefairy Doll. Talk to him and he will give you the doll (only after you've talked to Copycat and she has mentioned her doll). Go back to Saffron and go to copycat's house (it is in the northern part of the city) amd give her the doll and you will get the ticket.