I’ve not played a lot of NSMB Wii rom hacks but out of the few I have the worst has got to be “New Super Mario All-Stars HD”. It’s so bad it’s actually pretty funny in a way. It’s real bootleggy, so much so that the creator actually makes you pay for the rom last I checked. (Seriously. Imagine having to pirate a rom hack.) The game is fairly glitchy with the occasional random crash here and there. It also steals a lot of custom assets from Newer SMB without credit, and I’m sure the custom music is stolen without permission too. Not only that but the only language is Portuguese, just to add to that classic ‘90s bootleg feel.
Only download if you are super curious (that is, a free version if you can find it. It’s out there). It can be fun multiplayer, especially when you all are making fun of it. Otherwise just look up a playthrough on YouTube.