if im not mistaken, u have to go through diglett cave, via moving snorlax with ur radio pokeflute music.
There is no Viridian Forest in D/P. Viridian forest is a location in the Kanto games only.
He won't be in viridian at first he will be at cinnibar island if you talk to him he will go to the gym in viridian city go to viridian city to battle him.
Viridian city is north from pallet town.
In order: Cianwood City, Mt. Mortar, Vermillion City, Route 13, Bill's House. You're welcome.
Use a super rod in the water at viridian city.
In kanto, south of pewter city, north of viridian city.
You Cant be in Cerulian if you haven't been to Viridian.
You go to Viridian City then go up get through the Viridian forest and then you get to Pewter City
You can get Pikachu in the Viridian forest south of Viridian City.
In the Kanto region above Viridian City
Through the Viridian Forest. It says so in game,
go through viridian forest