Instructions
Trade someone for the Shiny Pichu if you did not get it during the 2010 GameStop promotion. If you have the Shiny Pichu and it has already evolved to a Pikachu or Raichu, it will still trigger the event.
Put the Shiny Pichu in your first slot, and leave one slot empty.
Enter the Ilex Forest west of Azalea Town in the Johto region.
Go the the center of the forest and find the Ilex Forest Shrine. Once you find the shrine, a female Spiky-eared Pichu will appear and join your party. She will be holding a Zap Plate and will have her own unique attacks and sprites. This Pokemon begins at level 30 and cannot evolve or be traded outside of HeartGold or SoulSilver.