You talking New Super Mario Bros Wii or New Super Mario Bros on DS? Both are top notch, but if you haven't played it yet Super Mario Wonder is IMO the best 2D Mario since Super Mario World on SNES. Definitely wouldn't bother emulating Switch though when you can buy Erista Switch that can be softmodded or Switch OLED that you can pay someone to hardmod or do it yourself if your soldering skills are elite (the modchip is supposed to be really difficult to install on the Switch OLED and is way beyond my skills). Super Mario Maker 2 on Switch is also outstanding even just counting the built in levels.
Have you played Muramasa The Demon Blade? That's IMO the best 2D platformer on Wii, just amazing art and colors. Plus there is a 4k mod for it on Dolphin, though I forget the details on setting it up since I haven't played it in years. But it looked way better on my 28" 4k IPS panel in Dolphin than even playing natively on my OLED Vita.
Don't know if you have heard and these aren't 2D games, but there are reverse engineered ports of Super Mario 64, Ocarina of Time, and Majora's Mask out now. Pretty sure they have been ported to Android as they're seemingly on everything. Just awesome playing Ocarina of Time at 60 fps instead of the 20 fps the N64 could run it at, though if you have a high refresh rate monitor I think you can run it up to 256 fps, at least on the PC port. The reverse engineered Ocarina of Time project is called the Ship of Harkinian. It's way better than the official 3DS port Nintendo did. I forget what the others are called. Supposedly Twilight Princess is close to getting reverse engineered too.