Things You'll Need
Instructions
Find a friend with the Pikachu Colored Pichu or find a copy of Pokemon which already has one on it. This Pichu was only available in a special Wi-Fi event and a special Gamestop event, so there is no way to obtain one in SoulSilver without either having procured it through an event in the past or knowing someone else who has one. This will be the hardest part of the process as they are fairly hard -- but not impossible -- to find.
Get the Friend Code for the Pokemon game on both DSes. To do this, open the in-game menu, select "Use" on the Pal Pad in your bag, and then select "Code." If you don't have the Pal Pad, it can be picked up at the Oreburgh City Wi-Fi Club. The DSes must also be connected to the DS Wi-Fi network. For a guide on how to connect to the network, look in the "Resources" section of this article.
Write down the Friend Codes for each Pokemon game. On both DSes, open the menu and select "Use" the Pal Pad in your bag. Select "Register Friend Code," and give your friend a unique name (it doesn't matter what name you use). Press "OK," and then enter the Friend Code you have written down (enter the one for the DS with the Pichu into the SoulSilver game and vice-versa). Press "OK" again, press "Yes," and your friend will be added.
On both DSes, enter a Pokemon Center and go to the Pokemon Wi-Fi Club downstairs. Talk to the woman who is at the desk and tell her you want to connect to the Nintendo WFC. Follow the instructions onscreen to connect to the WFC. When it connects, it will show which of your friends are connected to the WFC.
On the DS with Pichu, select "Invite" and then "Trade." On the other DS, select the name of the friend with the Pichu and press "Apply." This will open the trading screen.
Select the Pikachu Colored Pichu on the trading screen on the DS that has it. On the DS with SoulSilver, select any Pokemon you wish to trade. Enact the trade on both DSes, and you will have the Pikachu Colored Pichu.