It is possible to get the three starting Pokémon – Bulbasaur, Charmander and Squirtle – in "Pokémon Yellow." Typically, a player has to choose one of the three and cannot add the other two unless he does so by trading Pokémon with another player. Each method used to catch the three starter Pokémon carries a reminder of an episode of the Pokémon TV show.
Visit a house near the Cerulean City Pokémon Center
Visit the house immediately to the west of the Cerulean City Pokémon Center. Any player whose Pikachu is in a good mood finds that the lady in the house offers a Bulbasaur that she has nursed to health, representing Melanie's care for injured Pokémon in the episode "Bulbasaur and the Hidden Village."
Talk to the trainer near Nugget Bridge
Head to the raised platform north of Nugget Bridge in the northwest corner of Route 25. Talk to the trainer there. He claims that he is not a good trainer and offers a Charmander. The trainer is reminiscent of Damien's abandonment of his Charmander in the episode "Charmander the Stray Pokémon."
Talk to Officer Jenny
Beat Lieutenant Surge at the Vermilion Gym to obtain the Thunder Badge. Then, go to the middle of town to talk to Officer Jenny. She turns over a Squirtle, claiming he is a mischief-maker, just as occurred in the episode "The Squirtle Squad."