I have found some codes recently that I would like to share with you. I am not sure if this is all of the codes or there is more to find.
Those are some of the codes I know some of them unlock the same thing. I also want to tell you a cheat for restarting the game. When you are on you options menu when you first turn your ds on, click on the game for petz dog pack and before the screen pops up that says prees start you have to hold down l,x,b,and select at the same time. Then a screen should pop up that says "Are you sure you want to restart the game?"