The button configuration on the 3DS VC is indeed a pain in the behind. Recently played through Shantae and it took a while getting used to. Luckily the Wii U VC lets you configure the buttons as you wish and I see no reason for why Nintendo shouldn't add that option to the 3DS VC.
As for SMB Deluxe, I didn't get the game because I'm a lazy fool who forgot to link his NNID in time. 








