Unfortunately the Wii U isn't powerful enough for that. (heck, I don't think even the PS4 could emulate the Xbox 360 perfectly if you think about it.)
But there are some cross-platform games that were released for the Xbox 360 that also made their way to the Wii U:
* Batman Arkham City, Origins and Blackgate
* Injustice
* Mass Effect 3
* Assassin's Creed 3 and 4: Black Flag
* Watch Dogs
* Darksiders 1 and 2
* Sonic & All-Stars Racing Transformed
* Skylanders Giants, Swap Force, Trap Team, SuperChargers and Imaginators
* Just Dance 2014, 2015, 2016, 2017, 2018, 2019 ( The Wii U version is actually the PS4/XONE/Switch version )
* Rayman Legends
* Deus Ex: Human Revolution
* Splinter Cell: Blacklist
* Call of Duty: Ghosts and Black Ops 2
* Need For Speed: Most Wanted ( 2012 version )
* Tekken Tag Tournament 2
* Trine 1 and 2
* Bit.Trip Runner 2
* Resident Evil: Revelations
* Minecraft
* FIFA 13
* Scribblenauts Unlimited
* Ninja Gaiden 3: Razor's Edge
These are just a few that I can remember, there are probably many more, not to mention that the Wii also received several Xbox 360 and PS3 games (since the Wii was from the generation of these consoles) and Wii games can be played on the Wii U.