1. Complete the training courses: As your dog progresses through the training courses, they will earn medals. Once your dog has earned enough medals, you will be able to trade them for a rose or a lucky collar at the Prize Booth.
2. Participate in competitions: You can also win a rose or lucky collar by participating in competitions and winning first place.
3. Speak with the pet shop owner: Sometimes, the pet shop owner will offer a rose or lucky collar as a gift to your dog.
4. Receive from other players: If you have friends who play Nintendogs, they may be willing to give you a rose or lucky collar.
5. Use cheat codes: There are several cheat codes that you can use to obtain a rose or lucky collar. However, please note that using cheat codes may void your warranty and/or get you banned from online play.