Your adventure begins in Pallet Town, your hometown. After Professor Oak's introduction, you'll find yourself in your room. Head downstairs and talk to your Mom. She'll give you some advice.
When you try to leave town, Professor Oak will stop you, warning you about the dangers of the tall grass without a Pokémon. He'll then take you to his lab, where you'll meet your rival, Blue. Professor Oak will offer you a Pokémon, but Blue will snatch the Eevee he intended for you. Instead, you'll receive a special Pikachu who will follow you everywhere!