I have never seen one pokemon modifier code that work with gameshark. And if you find a pokemon you will only find houndoom or sunflora. I got a US version and when they say that the codes work 100% and it's for US version it will:
1. lagg the game.
2. freeze the game.
3. find houndoom or sunflora.
4. nothing happens even if the gameshark codes is enabled.
Here's two of the link's:
So if you figure a way to make them work or find cheats that work post it here.