New Super Mario Bros. U cannot be installed on a standard Nintendo Wii.

game is not forwards-compatible with the older Wii hardware. How to Install Newer Super Mario Bros. Wii

Performance: On a real Wii, you get a solid 60 FPS in single-player. The game is highly polished and rarely crashes if installed correctly.

Option A: Play on a Wii U

• Method: Buy the disc or download from Nintendo eShop (before closure) or purchase New Super Mario Bros. U Deluxe on Switch.
• No hacking required. The Wii U is backward compatible with Wii games, but not vice versa.

Part 3: Why You Should Avoid “Free NSMBU Wii ROM” Download Sites

If you ignore the technical impossibility and search for “new super mario bros u wii roms for wii install” and click on the first few links, you will encounter:

He jumped into the first level, "Acorn Plains." As Mario donned the Flying Squirrel suit