First off, name yourself Gary, and your rival Ash. As soon as the game starts hit save. Don't head to the grass, head to Oak's lab and talk to Gary 5 times. Then walk around Pallet town before heading to the grass. Oak will catch Pikachu, and you'll head to his lab. This time 'round Oak will tell "Ash" to get the pokeball on the desk. Oak'll attemtp to give you the Pikachu, but Ash will run over and take that one. Oak will scold Ash for being selfish, and tells him to give you the Pikachu. While Ash walks over to you hit both L, and R, both 5 times, and hit up, down, A,B. You must hit all this before he gets to you or you'll have to turn it off and start back at your house. If done right, Ash will trick you and give you Eevee.