Normally the guard won't let you past him in order to go to Celadon City to solve this problem enter the Underground Path not to far from the guards station and pass through it when you go up the stairs and out the exit you will appear on a Route go west to reach Celadon City.
go to the city with the big store and go into the tan skyscraper and talk to the ld woman
you must go to celadon city and enter a building with an old woman surrounded by Pokemon. she will give you a drink and when you take it to the guard he will let you trhough.
There is no Veilstone City
You need to go into the big building in Celadon City where there is a lady who gives you tea. Then you give the guard the tea and you can pass.
at cerulean city.
fucshia city
Celadon city
celedon city
vermillon city
Pewter City
Its on the Route west of Celadon city and east of Vermilion city.
well you go inside the city inflantrate team rockets base (the tallest building in the city) and the the gym will open so you can beat the gym leader