I have 2 (1 from Soul Silver, 1 from Heart Gold).
But apparently, 1 PokéWalker is defective, because of an transmission error (and so I've lost my Notched-Ear Pichu forever), and 1 PokéWalker is still in my Heart Gold box; never even touched it.
Oh that thing...
PokemonMaster was a nickname my friend gave me.
I have SS thank you very much. I not very familiar with things outside the games and Pokemon Adventures. I've never used it. Its probably still in SS's box.