While not DS games, many titles on the 3DS hardware utilize QR codes for bonus content. For example:
If you want to explore more hidden secrets, I can help you find specific codes. Let me know: Which you are playing? What kind of item you want to unlock? If you need help fixing a camera error ? Share public link nintendo ds games qr codes
still have active communities sharing QR codes for custom content? How to Scan a QR Code - Nintendo Support While not DS games, many titles on the
Point your camera at a QR code hosted on sites like the hShop or community forums. While not DS games
Nintendo used QR codes for specific metadata and minor content rather than the games themselves: Mii Sharing : In games like Tomodachi Life