To get the EV Reducing Berries, you need to go the Dream World and grow them in your Garden. Before you can obtain the Dream World, you have to make a Pokemon Trainer Club account, which also needs the consent of your "Parents". Here is the Link:
After you and your "Parent/Guardian" sign up there, you have to make a Pokemon GL Account, which will show up when you sign in. It will ask for your Game ID or what Game Card you are using. You do need WiFi to complete the process which is to put a Pokemon to sleep and sending them to the Dream World via Game Sync. I will let another user explain that since I have no DW yet, so i dont know the complete process.
That is the Global Link Website.