Instructions
Defeat the first gym leader at Oreburgh City. Roark is a gym leader that specializes in Rock types like Geodude and Onix. Get the second badge from Gardenia, a gym leader that specializes in Grass types. Obtain the Cobal badge by defeating Maylene, who focuses on Fighting types.
Heal your party at the Veilstone Pokemon Center. Teach your party Ground-type moves, such as Dig, Mud Shot and Magnitude. Make sure at least one Pokemon in your party can inflict various status effects, such as Burn, Paralysis, Sleep, Freeze, Confusion, Attraction and Flinch.
Visit the Veilstone Department Store. Collect Cheri berries or purchase Paralyz Heals. These items will heal your Pokemon if Pikachu paralyzes your Pokemon. Buy Super Potions and Lemonade for your Pokemon. Purchase 10 to 20 Ultra or Great balls to capture the Pikachu.
Teach a Flying type the move "Fly" (HM 02). Use "Fly" to travel back to Hearthome City in less than a few seconds. Leave the city by taking the South exit, which leads to Route 212. Beat all the Pokemon Trainers there if this is the first time you visited this route.
Visit the Pokemon Mansion on this route. Head to the patch of grass to the rear of the mansion. Walk in the long grass until you encounter a Pikachu. Use Ground type moves to lower the Pikachu's health to the red zone and inflict a status effect on the Pokemon. Throw Great or Ultra balls at the Pikachu until you capture it.