For bulbasaur you look in the southern part of pallet town and for charmander you go to the mansion on cinnabar island and look for 10 minutes
First you pick one of them for your starter pokemon the you run in the pokemon mansion for ten minutes and right when it strokes ten minutes a charmander will appear. Hope I helped...
You would have to choose one of them as a starter pokemon.
You can't catch them but you can start with one of them or trade with your friends. .