So, from May 6th all the way until June 25th, you can get the Winner's Path Pokewalker course on Wi-Fi. It's actually useful because you can find nice battle items like choice items, and the Pokemon know special moves(mostly moves you can get from move tutors/TMs P:) and have nice items as well. More specifics, like how often you encounter Pokemon, can be found here: http://serebii.net/heartgoldsoulsilver/pokewalker-area.shtml#champpath (serebii because the url code doesn't like bulbapedia's apostrophes)