My SoulSilver and Pokewalker are both pre-owned by different owners, so my Pokewalker is already registered with its previous owner's SoulSilver, not mine. How do I register my Pokewalker with my own copy of SoulSilver?
Start the game on the Nintendo DS.
Select Connect to Pokéwalker from the Main Menu.
You will now be on the menu that says, Save, then go for a Stroll. Press and hold Down on the D-Pad, X, and the L Button all together.
The game will now caution you that you are erasing the Pokéwalker, and all other data will be lost. Select Yes to proceed.
Now select Erase Pokéwalker Records, and then when prompted select Connect on the Pokéwalker to complete the process.