Hey,
I've got a jap version of Black with an english patch and wen i tried the code, first time it worked fine, happy with my lvl 1 bulbasaur... but tried it again didnt work =/.
i get the 649 M balls and 100 U balls but the pokemon dont change any more.
might also add that this code and the "catch trainer pokemon" code r awesome got da 3 starters