You can fly there or go west.
in kanto, east of pewter city and west of cerulean
you have to wake up a snorlax at digletts cave
Pewter City
She is in Cerulean City, in the Cerulean Cape. You will have to battle your way there however.
By going from Pewter City to Cerulean City, you just hop off the ledge. From Cerulean City to Pewter City, you can't. You have to go around and into Diglett's Cave.
Go to the cave between Cerulean City and Pewter City.
Cerulean city is in Kanto region. You can go through saffron city to get there. It is the north exit in saffron city!
At the top of pewter city in the kanto region
talk to the man on the platform in pewter city
Its in Kanto to the right of Pewter city.
go down at pewter city
to pewter city