This gives me an Idea. Nintendo could use QR codes in Super Smash Bros. 4. Since the Wii U and 3DS will both have cameras. You could unlock additional character colors and trophies. I'd prefer it over the conventional means of unlocking stuff.
Back on the topic of Mario Tennis Open. It Looks pretty awesome. I'd consider it, but I heard Neal say the online was laggy. I know how slow my connection is, I couldn't even play SSBB. I could Mario Kart Wii though.