you start a new game, you will see Prof. Oak. He will tell you about
himself and about Pokemon. Then, you enter your name and your rival's
name. When the game begins, you will be in your home with a SNES. Walk
to the bottom floor and out the the door and into the tall grass. Prof
Oak will stop you and tell you that wild Pokemon appear there. He will
take you to his lab where you can choose your starter Pokemon.
is the easiest choice because it will get you through the first few
gyms easily. Squirtle is also a good choice because it will also defeat
Brock. Charmander is the worst choice because it will make it hard to
beat Brock and Misty.
In Pokemon Yellow, you get Pikachu instead of the starters. Later on, you will get each of them.
After you pick your starter, your rival
will pick whichever pokemon is powerful aganst your pokemon. Then, the
first battle will start. Gary will have a level 5 C/S/B (in yellow, Eevee) and you
will have a level 5 (insert the name of your starter here.) Keep using
scratch/tackle and you probably will win. If you defeat him, your
Pokemon will grow to level 6 and you will gain 200 Poke. If you win, he
will leave and say "Smell Ya Later!" Your pokemon will also be healed.