This is the first and easiest place to go through just follow the path until you reach a big building go past there keep going north until you reach pewter city. The easiest way is to use repel and have charmander or a pidgey before you go to viridian forest.
in Pokemon heartgold, soulsilver, firered, and leafgreen it is north of Viridian city
yo go out of the veridian forest and talk to prof oaks aid and he gives it to you nooooooooooooooooooooooooooooooooooooooooo
North of Veridian City and south of Pewter City.
the veridian forest.
Its right above viridian city.
You catch Pikachu in Veridian Forest
On Route 204 - south - with the Firered cartridge inserted(DS lite only), by putting Caterpie into the PalPark from Firered or Leafgreen, or trading it from Heartgold(Routes 2, 30, 31, Ilex Forest, National Park, Veridian Forest, or Bug Catching Contest) or Soulsilver(Bug Catching Contest).
Veridian city the gym leader id Giovanni
The Viridan Forest is a little ways south of Goldenrod City.
You can get a pikachu in veridian forest or in the pokewalker
go through viridian forest
(Pewter city) through Viridian Forest