Dratini can be found in the sarfi zone by fishing.
Growlithe can be found on route 7, route 8, and Pokemon mansion.
Pikachu is in Veridian forest you just have to get lucky to find it. You can also get it in the power plant.
"Don't walk behind me; I may not lead. Don't walk in front of me; I may not follow. Just walk beside me and be my friend."