There are really no good sites that have Pokemon stuff right now... ill find some later for you. But i do have one for cheat codes. All you do for this one is click on it and then you will have the Pokemon choices for the games that you want codes for. Click on the version you want and the codes will come up.
And then heres another one... the "official Pokemon website"... personally i dont think its that great but you can check it out if you want.
Cheat codes for Pokemon!!!