The Pokéwalker is a device specifically designed to work with Pokémon HeartGold and SoulSilver (not just SoulSilver). It's not compatible with any other Pokémon game.
Here's how the Pokéwalker works:
1. Transfer a Pokémon: You send a Pokémon from your HeartGold or SoulSilver game to the Pokéwalker.
2. Walking and Training: The Pokémon walks around in the Pokéwalker's internal world, encountering wild Pokémon, earning experience points, and potentially finding items.
3. Transfer Back: You can then transfer the Pokémon back to your game with its improved stats and any items it found.
While the Pokéwalker is a unique feature for HeartGold and SoulSilver, it's not compatible with other Pokémon games.