Print this Get Bulbasaur, Charmander and Squirtle.
Unfortunately, in Pokemon Blue and Red, getting all three of the Main Starter Pokemon (Bulbasaur, Charmander and Squirtle) takes about half or all of the game to do. Pokemon Yellow isn't the same. In fact you could have all three by the time you have completed as little as 3 or 4 Cities!
It starts with Charmander. Get to Cerulean City. This is the Blue City with Misty as the Gym Leader. First defeat Misty. You're Pokemon must be around Level 20 or higher if this Gym is a breeze. Then go North where there's two passage ways. If you go up the Right one you notice there's a wall blocking which means you must go up the Left one.
Beat all of the Nugget Guys, including the final guy at the top. Once again, make sure your Pokemon are Level 20 or higher for this challenge to be a breeze.
Now after defeating all of these go straight up and left. There should be a guy standing in a Box with a PokeBall nearby him. It's not a Pokeball, but that isnt the concern. Talk to this guy, and he will give you his Charmander. Next is Bulbasaur. Go right from the Guy who gave you Charmander. Go through the tiny Forest-like enviornment, and go through the Trainers. Then you get to a big House. This is Bill's House. Once entered you'll find a Pokemon standing there. Talk to it, it's actually Bill. He tells you he's messed up an experiment. He tells you to go and switch the Switcher thing or something. As he enters the Chamber, go to the Computer and Press A to do the Job. He thanks you and gives you a Ticket to the S.S. Anne Cruise Ship involving Trainers. Ignore this and head back into the City. Now what's this? The House just to the Right of the Passage Ways heading North has some Police Woman at the front of it, and she's subsided from the Door allowing you in. Go in and straight out the hole in the back of the House. Defeat the Team Rocket Person and they'll give you Dig. Give Dig to one of your Pokemon.
Now go back to the Pokemon Centre. There's a House just to the Left of it. Enter and there's a Woman surrounded by lots of Pokemon. Talk to her and she will give you her Bulbasaur. And there you have it. A Side Note: My Pokemon were Level 20s and Over naturally from my heavy Training Prior to entering Cerulean City, so I'm not sure if your Pokemon HAVE to be Level 20 or Over to recieve the Pokemon, but I'd advise you to have them over Level 20 to beat Opponents as well as recieve the Pokemon.
Next is Squirtle. This will be less specific.
Go back to Cerulean City. Go into the House Team Rocket wrecked and go out the back of it.
Go around the House and head straight down. Not back in by the Gym, but further downards. Head all the way down the Path wih two lines on either Edge until you find a small building. Enter it and go through the Underpath.
Once you've got out of the Underpass and out of the next Little Building, there is a big patch of Grass. Head left and follow the Grass-less Road. Take on the Challengers. After defeating the Trainers and continuing to follow the Path until you get into a City where the Colour goes Orange. I don't know the name of it.
Get on the S.S. Anne (To the Right of the Mart) and get the HM Cut on the Ship. This is by Getting to the Captain who is being Sick in his Bin. You pat his back and he gives you Cut.
Defeat the Gym Leader Lt. Surge, and then go to Officer Jenny who is to theLeft of the Mart and she will give you Squirtle.
And there you have it!