If your DS lite has compatible Wi-Fi, you can use Pokedoc's tool linked to in the first post. In case it doesn't work, you'll need to DLDI patch it. DS Organize includes a DLDI patched version of itself for the Games 'n Music, which is basically the ARDSi. Launch that, and use it to run Pokedoc's tool. Don't use it for much else as DS Organize can easily corrupt your card.
If you don't have compatible Wi-Fi, you'll need a USB Adapter (I recommend the NDS Backup Adapter Plus).
If you don't feel like spending money on that, since you can use ARDS codes, you can try to recreate your Pokémon in Pokegen.