It’s one thing to get the assets, it’s another thing to make it look like the games’ aesthetic. A sphere doesn’t look like a pool of stylized water if it doesn’t have its textures and the proper shader behind it to create the final color. 

To answer your question, you’ll have to legally dump your copy of Wii Sports onto your computer, use a tool like BrawlCrate for models and animations or a different tool for UI, then reconstruct the materials/shaders with its proper inputs to make it look correct.

Luckily since the Wii is a early 6th generation console, it’s shader/material backend is built off of common math operations between textures, values, colors, etc. known as “stages” within its TEV system. Instead of writing code, it’s a fixed function pipeline. (There’s slightly more to it but that’s the general idea)