You'll be needing an emulator called No$GBA, since it runs all .nds ROMs. VBA won't run it, unfortunately. ;;
EDIT: Be sure to look for No$GBA 2.6a, since that's the only one that'll run the game. Also, don't forget to download an anti-freeze patch, since Nintendo installed some anti-piracy thing into the ROM, so it freezes at every opportunity, like right after you tell Prof. Oak your name. :[