You can do Download Play through Local Multiplayer. I've done it before; the person with the game opens a group and the other(s) play through the Download Play app. Available gameplay modes are singles/doubles Exhibition Matches, Ring Shot Challenge, and Super Mario Bros. Tennis. As for character selection, you can use your Mii, but with no customized costumes/equipment, and all of the Mario characters available at the start of a new file, with the option to Star any of the characters that the person has unlocked as a Star character. Neither player can select any of the QR characters.
3DS FC: 2320-6610-8180 (Feel free to add me, just let me know so I can add you too)