Mario Kart 8 did have Battle Mode. It had no Battle Arenas, and made you do it on the courses.
I know exaggeration from my part, but it basicly was non existent considering it used regular tracks, for my taste anyway.
I have one plus for the wii U though, even though the actual console and games weren't that great I did enjoy the nintendo directs allot, those where infinitely better than the ones we have in the present. The vibe of the company was very nice during that era.
Always loved the Wii U and never thought it got a fair shake. Honestly, most of what makes the Switch great is just Wii U and PS3/ XBox 360 ports.
I'm curious what made the switch so great if where talking wii u ports, since I assume you mean that switch first party games where less impressive.
Aside from mario kart 8 I can't really see what the wii u brought that wasn't done better on switch or is that incredible to sell the system. Botw is hard to classify as a wii u game considering it came out when the wii u died it's pretty much a switch game and they released at the same time.
You can like 3d world but surely most would agree that mario odyssey made a way bigger impact and is just one of the best games in the series.
Still ignoring at least mario kart 8 and botw, What wii u port is way better than what we got in switch exclusives and would make that entire library less impressive compared to said wii u games. allot of wii u games have superior next number entries on switch or main games that didn't even exist in the previous gen.