Obtaining the Starters in Yellow Version
In Red and Blue Versions, you get either Bulbasaur, Charmander, or Squirtle as a starter Pokémon. It’s your first Pokémon, but in Yellow, this is different. You get Pikachu as a starter Pokémon in Yellow, but you can get the original starters later on.
Once you get to Nugget Bridge, just north of Cerulean City in Yellow Version, there will be a boy there. Talk to him, and he’ll ask you if you want to take care of his Charmander. Say yes, and it’s yours!
Bulbasaur is a little harder to get. You have to make Pikachu happy enough, then talk to a girl in the house to the left of the Pokémon Center in Cerulean City. You can make Pikachu happy by giving it Potions, even if its health is all the way up. That, or you can just level it up and not let it faint.
You can obtain Squirtle after you beat Lt. Surge in Vermillion City. Officer Jenny will be standing outside, between the gym and the Poké Mart. Talk to her to get Squirtle.
All three of the starter Pokémon will be at level 10, early enough in the game to train them and make them strong battlers.