Right at the beginning of the game when you are given the usual Charmander, Bulbasaur, Squirtle choice, pick none of them. Physically run away from them. The game will jump them over to try and follow you, but by the fourth time you do this, it gets the message you don’t want any of them, and surprise! There’s Pikachu!
How to play pokémon go?
Turning off AR (augmented reality) in Pokémon GO switches off the camera and gives you a plain background. It allows you to catch a Pokémon without aiming your phone's camera at it, which makes it a lot easier! Another benefit is that it saves battery power. To turn off AR you'll need to find a Pokémon. Tap on the Pokemon to engage it and the AR toggle will pop up in the upper right-hand side of the screen. Make sure to toggle the AR switch before you capture the Pokemon.