Your intimate Snorlax knowledge won't be worth a Charizard in a tropical storm when Pokemon Black/White hits US soil. Game Freak's Junichi Masuda revealed an interesting design decision that makes it impossible to encounter older, more familiar Pokemon the first time you run through the game. You'll only meet brand new Pokemon created for the title in your initial run, Masuda said.
Masuda explained in his blog post, which has been translated by Andria Sang, that Game Freak wanted to level the playing field and make the game feel alien to Poke-vets and newcomers alike. New Pokemon and new attacks will certainly do that.
Masuda acknowledged on his blog that creating new Pokemon for the game has been rough. I'd imagine. I think he and Game Freak have added a water, fire, rock, earth, or whatever modifier to every known cute animal this side of the chinchilla. Perhaps it's time to start riffing on the cast of Dawson's Creek or something. James Van Der LEEK. Get it? He's that jerk, except he's a plant. Please remember to tip your waitstaff.