1. Until Just Dance 2020 replaced it, MK Wii was the #1 seller in the Wii Games section of Amazon.com. It will return to #1 in the not-to-distant future.
2. These are new sealed purchases of MK Wii Nintendo is reporting. That's going to be almost exclusively Japan, Korea, North America, Australia, and Europe with a bit of South America. Show me evidence that the Wii is popular in the Middle East or Africa or that any retailers are importing it there. No way it's more than a few hundred copies.
3. Nintendo reported in 2018 that they sold over 40,000 copies of MK Wii in one quarter, so MKW sales in 2019 are actually about half of what they were last year.
4. Not many Wiis were still being sold by the time the occasional bundling of MK Wii began. And the Wii Mini was very, very unpopular. This is not like Wii Sports at all.
5. There aren't enough CTGP players in the history of the project to sell 40,000 copies to in the history of the Wii, let alone in the last 6 months, and...
6. Almost all CTGP players bought MKW a long, long time ago and those that didn't are likely to buy used. So no, it has nothing whatsoever to do with CTGP.
Getting back to Just Dance 2020 for a moment, which I preordered (just as I have every year since JD 3), it is important to remember who this console was made for and who bought it. It was us "casual gamers" (in my case "exergamer") that made the system as popular as it was. Without us buying it for Wii Sports, Zumba, Wii Fit, JD, Exerbeat and EA Active the Wii would have just been a slightly more powerful GC with motion controls that most gamers hated. So it would not have sold even half of what it did.
And what was the one "game" that "we" purchased? Mario Kart. In fact I only played it for the first time here in 2019 in spite of owning and using my Wii continuously since 2007. I purchased every single exercise game and almost every dance game including imports. I didn't buy even one "game" though. Millions of us never stopped using fitness and dance games which is why Ubisoft kept making them for us. Just this year I decided to start learning what else I could do with my Wii and played MK for the first time. Looks like Mario Galaxy 2 is next on my list. Since I've not played a platformer since Donkey Kong in the 1980s, I have a lot of catching up to do. So do a lot of us casual gamers. Expect Wii titles to continue selling well into the future. It's really the least dead of the pre-2014 consoles.