I don't know, a new game in the generally dry Nintendo Switch early year physical release window would have done decently either way. With similar reviews I could see a million or 1.5 million. 

Let's not forget how well Indie Games took advantage of it. I won't disagree it probably would sell less, but I could still see it doing well. 

I'm curious as to where the Nintendo-Ubisoft partnership goes from here. I'm willing to bet that there is another Switch exclusive in the works by Ubisoft, which may or may not be a follow up to Mario+Rabbids. And we already know that Trials Rising will be on Switch too. While I don't ever see any of Ubi's newest big hitters come to switch (tom clancy, far cry, assassins creed), I do hope they bring some of the smaller games over, such as Trackmania Turbo, and give us some older games Assassins Creed IV black flag, Farcry 3 and 4, Splinter Cell Blacklist, and more. Infact, two of those listed games were on the Wii U, so I don't see why it's not possible.

Davide and his team had to not only keep asking permission for their ideas but also they were given frequent feedback from them.The "not jump" guideline was one of them, but the wacky guns were also another of them.Here is a quote from an article about the game:

Source:

https://gadgets.ndtv.com/games/features/mario-rabbids-kingdom-battle-nintendo-switch-making-of-1731582

"While Ubisoft Milan handles the game’s development, Nintendo has played a supervisory role through and through."

“[Regarding the gun] we were the first and biggest filter before reaching Nintendo. The whole presentation of the weapons happened in Kyoto, but before going there we knew that it was the first time Mario was holding a weapon, we knew that it was possibly working only if it was merging well with the tone of voice, the light-hearted kind of aspect," says Soliani. "We used a lot of disproportion to create our weapons, we didn’t want them to look real, but at the same time we wanted the player to understand the function by just seeing the visual. When we arrived [at Nintendo] we had a vision of the weapons that was almost final, and they accepted our intention.”

As for your sales argument, Nintendo dosent need to provide numbers.Nintendo is one of the few companies that, alongside Capcom, does provide quaterly reports on their games performance, and they only report on games that have sold more than 1 million, are in the top 10 best selling software(that they own), or had an exemplary performance.The difference betwenn first party and second party games is that there is an additional developer involved with the game.So even if Nintendo has some sort of rights over that game, they will most likely respect the other developer wishes over if they want, or not want to, release the numbers.

And I mean, the game has Mario on the game.Mario.Not only him, but Peach, Luigi, Yoshi, Bowser and so on.Nintendo properties.How can someone see that and think its a third party game(in another words, that Nintendo had zero involvement or zero rights over it), is head scratching.

I dont know.It wouldnt have performed as well, that much is true, but it would have been a quality game nevertheless.Given that and the lack of big quality games earlier on its life, I think it isnt beyond reason to think it would have sold at least 1 million by now.

I was assuming that the game tone and vision would remain the same.But yeah, you have got a point.Hell, you are probably right.

Got Mario + Rabbids last week. Wasn't too sure about it after my first play session just going through the first couple stages...game starts slow and super easy. But I'm at the beginning of World 3 now and I'm liking this game a lot. It started ramping up in the middle of the first world and has continued to ramp up throughout the game. I don't buy many $60 games anymore, but I got this half off at $30 and I think it is well worth the $30. Fun game that just absolutely exudes charm! Glad to see it selling so well.

A really great and fun game, well deserved.

Well deserved. Here's hoping we get a sequel to it at some point in the future

It's officially a third party game, so there is no head to scratch. And if you ask yourself how a game with Nintendo characters in it can't be a Nintendo game, I have a good answer:

But if you still wanna think it's a second party game, feel free to do so

Smash is a Nintendo game developed by Nintendo( or that Nintendo outsource some of the development to others), and thus, it is a first party game.

Kingdom Battle is, by definition, a second party game.A third party exclusive(since thats the discussion) would be Octopath Traveler, just to give an example.But if you feel like calling Kingdom Battle a third party game, because thats what it feels like to you, thats your prerogative and thats more than fine.