Obviously, 2015 had some residual support from Mario Kart 8 and Smash (including significant DLC for both of these titles), but the Wii U beating its 2014 sales is nonetheless a huge achievement for Nintendo.
Splatoon was a complete dark horse and in many ways so was Super Mario Maker. I mean neither of these titles were concepts that Nintendo has ever tried before. 2014 was a safe year where Nintendo played it safe and rolled out it's big guns whereas 2015 was a year that Nintendo took some significant risks and they really paid off.
One thing that I hope Nintendo learns from the Wii U is that they should take creative risks on their software more often. There is so much creative brilliance at this company and I find that their conservative tendencies can really hinder it, at times.







