Board 8 > Went through and made a list of notable Wii U titles not on Switch.

(+) Yeah! (+)

There are certainly probably still some gaps even among significant releases, and plenty of obscure indie eShop stuff that I didn't even both with, but as far as I can tell this pretty much covers the most notable stuff. Feel free to add anything I missed.

Strictly exclusive to Wii U:
-Affordable Space Adventures - eShop-exclusive, so now impossible to legally obtain.
-Amiibo Tap: Nintendo's Greatest Bits - Another eShop exclusive but it's really just a bunch of retro demos. Not much of value is lost.
-Animal Crossing: Amiibo Festival - A board game.. game.. that requires Animal Crossing amiibo. Likely not being reissued.
-Devil's Third - I'm counting this as an exclusive since the Windows version was just the online multiplayer and the single-player campaign has still only ever been on Wii U. One of the most expensive Wii U games on the second-hand market.
-Dr. Luigi - Another one that died with the eShop. Was relatively popular and there's no proper Dr. Mario on Switch yet so I could actually see this one being rereleased now that it's unobtainable.
-Game & Wario - Relied heavily on the Wii U gamepad, so the odds of it being rereleased are slim. Used physical copies are surprisingly expensive.
-Kirby and the Rainbow Curse - Relied heavily on Wii U gamepad, so odds of a reissue are slim.
-Mario & Sonic at the Sochi 2014 Olympic Winter Games - Largely replaced by other Mario & Sonic games.
-Mario Party 10 - Another gamepad-heavy game that probably won't see a rerelease.
-Mario Tennis: Ultra Smash - Largely replaced by Mario Tennis Aces.
-Nintendo Land - Gamepad-heavy. Port unlikely.
-Paper Mario: Color Splash - Has a Paper Mario game ever gotten a proper port, Virtual Console/NSO aside? I know Wii U -> Switch ports seem to be a special case, but...
-Pokemon Rumble U - Died with the eShop. Does anyone care about Pokemon Rumble? I didn't see the WiiWare game get a port when that shop went down.
-Pushmo World - Died with the eShop but I could see this series getting ported to Switch.
-Rabbids Land - Never heard of it until I went to make this list but it IS an entry in a significant franchise, so...?
-Sonic Boom: Rise of Lyric - Sonic Boom flopped and Sega seems to have moved past it and let it die a not-so-honorable death. I don't see this being ported.
-Splatoon - Largely replaced by Splatoon 2 and 3.
-Star Fox Zero/Guard - I could definitely see these getting ported, hated as they were.
-Wii Fit U, Wii Party U, and Wii Sports Club - I don't see these ever getting ported. Nintendo has moved on from Wii Fit and Wii Party, and Switch Sports is a thing.
-Xenoblade Chronicles X - Probably the most puzzling game on this list, given that the rest of the series has been released/ported onto Switch. I'd expect this one to be rereleased someday, if not on the Switch then on its successor.

Games that are not strictly exclusive to Wii U but are not on Switch:
-The Legend of Zelda: Twilight Princess HD and Wind Waker HD - Technically the HD versions are trapped on Wii U but you can still enjoy these adventures on Game Cube (and Wii for Twilight Princess).
-Mario vs. Donkey Kong: Tipping Stars - Also released on 3DS; both were eShop exclusive.
-Mass Effect 3 - Notable for being the only Mass Effect release ever on a Nintendo system. Largely considered to be a vastly inferior port, plus it was released as a full-priced game the same date Mass Effect Trilogy was released on PS3 and 360. Even more confusing since this series is completely continuous and playing 3 without playing/transferring data from 1 and 2 would be just baffling. Needless to say it sold incredibly poorly.
-Monster Hunter 3 - Also on Wii and 3DS. Given the popularity of the series and this entry in particular I could see it getting a port someday, if not on Switch then on its successor.
-Mighty No. 9 - LOL
-NES Remix 1 and 2 - Though not an exact port, a large amount of their content was released on a 3DS compilation. Weird that these haven't been ported. They were fairly popular and it seems like it'd be an easy thing to port.
-Super Mario Maker - Ported to 3DS. Largely replaced by the sequel anyway.
-Super Smash Bros. for Wii U - Technically because of the 3DS version. Not like it matters; most of its content is in Ultimate.
-Watch Dogs - Released on Wii U as a full-priced title when it was already discounted on all other systems, and widely considered an inferior port. Naturally sold like crap and convinced Ubisoft that Nintendo gamers weren't interested in that type of game.
-Yoshi's Woolly World - Ported to 3DS, though it's almost universally considered inferior even with the new features.
-ZombiU - Ported to PS4, PC, and Xbone.

I was kind of hoping the NES Remix games would get ported for the 40th Famicom Anniversary but it doesnt look like it

It's kind of weird that the Switch has a touchscreen, but presumably games aren't allowed to rely on it because it would prevent them being playable docked. I assume there's an official policy banning handheld-mode-only releases, because otherwise Rainbow Curse and maybe even a new Elite Beat Agents would be no-brainers to release on Switch.

Also as a minor note, Sonic Lost World has crossover DLC levels based on Yoshi and Zelda that are exclusive to the Wii U version. And I think one of the Skylanders games has some figures of Mario characters that only work on Wii U.

I've played a couple games on Switch that didn't explicitly require handheld mode but were virtually unplayable without touchscreen controls. While I still enjoyed them, it didn't feel like I was getting the most out of the console. Kinda felt like I was playing on an iPad.

I dont think that Mass Effect 3 port is considered to be inferior, actually in terms of performance its a step up from the PS3 version and looks marginally better than the 360 version with comparable but slightly more inconsistent performance. The issue was the price and no 1+2. The porting job was always well received though and no surprise as it was Tantalus who would go on to do Twilight Princess HD.

i wish devil's third online lasted more than like 8 months, shit was fun as hell

although can't deny the lack of a player-base, every match had the same people in it coming and going ... but uh hey it meant you really knew the other players