Obviously 3D Mario. Nintendo knows they need to launch systems with either mainline Mario mainline Zelda.

So day 1 is gonna be 3D Mario along with some little casual game.

I'd expect next Mario Kart to be 1-2 months after launch like how they did with the Switch. So like if Switch 2 launches in September or October then MK would be the November holiday game.

Metroid Prime 4 I think we'll see at some point in 2025.

Next mainline Pokemon game will be holiday 2025. But I could see a side Pokemon game hitting both Switch and Switch 2 for the 2024 holidays to join 3D Mario and Mario Kart as the system sellers in the launch period. Like another Poke Legends game.

I could see a new DK game at some point in 2025 but not launch period.

Smash is obviously not going to be until late in the generation as we have several interviews from Nintendo that make it clear they haven't even figured out what they are gonna do for the next Smash game, so development of that game hasn't even started yet.

Launch day: 3D Mario, casual game

Launch period: MK, maybe cross gen side Pokemon game

2025: Metroid Prime 4, DK, mainline Pokemon

Nothing will sell the Switch 2 like a Pokemon that got BotW level reception and buzz. I think you’re kidding yourself if you don’t think Nintendo wants that. Otherwise they have to rely on something totally unforeseen like Wii Sports or Animal Crossing, and they don’t always get that 

One other thing to keep in mind for everyone convinced 3D Mario is so vital for launch: 3D Mario has historically not been a massive seller prior to Odyssey, which took years to get to such a high mark. Even 64 being hailed as the most revolutionary game ever at the time was like a 10m seller. Far from their juggernauts

One thing is Nintendo expecting Pokemon to move hardware. This is something the IP already do very well actually. As we can see no Nintendo Handheld ever sold less than 70 million units and Pokemon is a safe 3 spots on top 10 best sellers software list in any handheld system nintendo has. Currently, a third of Switch top 15 best selling software are Pokemon's, so you get the idea

Nintendo wanting Pokemon to sell like GTA is another thing entirely. For this to happen the game will need to be sold as a service for years plus be multiplat. Nintendo has no interest in maximizing software units with Pokemon. They can reach the blue ocean through mobile games, they do this already 

I think Prime 4 has a shot at 2024. The problem is that we're just getting hints of the possibility of it being shown soon.

Zelda may be interesting considering there are hints of a potential remake coming soon. How soon and how true it is, we'll see.

Smash is hard to predict. However, Sakurai has been teasing the possibilities of the next Smash game and his YouTube video output has been slowing down recently. So he may be in the process of developing/planning his next project.

If I remember correctly the top sellers for the N64 (based on media create white papers):

1) Mario64, 11.91M

2) Mario Kart 64, 9.87M

3) Goldeneye 007, 8.09M

4) Ocarina of Time, 7.6M

5) Super Smash Bros, 5.55M

Mario is Nintendo's mascot. Even if Switch2 will not launch with Mario, I think they will show something. Even though Zelda was the launch title for the Switch, we knew a Mario 3D was happening. There was a snippet in the November 2016 trailer and more was shown in the January 2017 presentation.