Copy pasting from a similar SONM thread:
Only including games I played on WiiU (for example, no BOTW as I have it on Switch and no WW as I have it on GC).
Mario Kart 8
The best Mario Kart (although the Switch version has the original WiiU game beat) and one of the best kart racers ever made. Near-perfect for local multiplayer, MK8 still gets played regularly with my housemates.
Super Mario Maker
Is there a game more perfect for the WiiU and gamepad than Super Mario Maker? Probably not. User created 2D Mario executed near perfectly - all we need now is an expanded sequel to add functionality such as multiplayer and (deep breath) slopes.
A brand new Nintendo IP that has firmly secured itself a place alongside the other Nintendo greats. As an online shooter Nintendo had a lot to prove with Splatoon, and they did it. Everything from the fresh aesthetics and music to the superbly balanced gameplay makes this one of the best shooters of recent years - who thought that would be said about a NIntendo developed WiiU game?
This launch game still remains one of the best uses of the gamepad. An excellent singleplayer experience with an underrated but very fun asymmetric multiplayer mode that completes the package.
I might prefer the 3DS port, but Hyrule Warriors is still an excellent game on WiiU. A near-perfect blend of modern Musou and Zelda, the love here for both franchises is obvious.
A mixed bag of games overall, but Mario Chase alone elevates this to games-to-always-have-to-hand status. The world needs more asymmetric multiplayer games, and we can only hope they are half as fun and accessible as Mario Chase.
I know what you're thinking, and it's true that the singleplayer here missed the mark (although I think it's still worthy of merit for the glimpses of how it could have all come together so much better). The online here was really the best part though, and it's a tragic shame that so few people played it. I had an absolute blast in the short time I spent with the game.
Mario & Sonic at the Rio 2016 Olympic Games
Or to give it it's proper title: Mario & Sonic Rugby Sevens. If Mario Chase is what makes Nintendo Land, Rugby Sevens is what makes M&SR2016OG (better shorthand on a postcard please).
Super Smash Bros. U
I'm far from a big smash fan, but the multiplayer appeal is unarguable and I do enjoy the new board game mode.
Fast Racing Neo
Until Nintendo finally give us a new F-Zero, Fast Racing will suffice. It's not quite on the level of F-Zero GX (what is?), but it's a great racing game.