The game begins in Pallet Town. Before going downstairs, interact with your computer in the top-left corner to withdraw a Potion.
Walk downstairs and speak with your mother. It’s time to get your very first Pokemon from Professor Oak. If you go to Professor Oak’s Lab, you’ll see he isn’t there. Go north into Route 1 to find the Professor.
After a little conversation, you’ll be able to select your first Pokemon.
You get to choose one of the following three: the grass- and poison-type Pokemon Bulbasaur, the fire-type Pokemon Charmander, or the water-type Pokemon Squirtle. Whichever Pokemon you choose, your Rival will get the elemental type that is stronger than your choice. Choose Bulbasaur and your Rival will choose Charmander.
Your Rival will challenge you to a battle as you walk out. You may want to save before battling so you can restart if you lose.
Attack with everything you have. You will only have two attacks, an offensive and a status attack, so this isn’t a very tough battle. If your Pokemon’s HP gets too low, use the Potion you withdrew from the PC to heal them.
After the battle, leave the lab and go north to Route 1.