How do you get new breeds of hamsters in pets hamsters 2 ds

Go to the Pet Store and talk to the shop keeper (On my game, he's called Garcia, but it'll probs be different on yours) Keep going in and out several times and chatting to him over and over, eventually, he will say he needs to go out and buy some supplies, leaving the assistant in charge. Leave the shop, go back in and there should be new items and new breeds of hamsters. Hope this helps! :)