You can find Pikachu in the Safari Zone just west of Lilycove City. It's kinda rare, so you gotta have patience. Hope this helps....
(edit) You can catch a low level Pikachu in the Viridian Forest also
South-East and South-West sections of the Safari Zone
Take a look here: http://www.serebii.net/pokearth/hoenn/safarizone.shtml
Usually in the first area of the safari zone.
The first area.
You catch Pikachu in Veridian Forest
you can catch a pikachu in the Pokemon mansion.
you start with a pikachu.................
CATCH PIKACHU UNTIL YOU CATCH A PIKACHU THAT HOLD THE LIGHTBALL.
You Can Catch Pikachu In Viridian Forest. Morning
You can catch Pikachu in Route 2 in Pokémon Gold.
You can catch Pikachu In back of the Pokemon Mansion Down from hearthome city.Also You can catch Pichus.
You can catch pikachu on Route 2 or in the Viridian Forset in the Kanto Region.you can get pikachu in Viridian Forest in Kanto.
you can't get a puple pikachu
you catch pikachu in the safari zone
you can catch pikachu in viridian forest but it is very rare and you can not catch the main three pikachu at the end.
Pikachu is found in the Safari Zone.