Pokemon was basically this on the 3DS, to the same extent that GTA was on the PS2. Speaking of which, Grand Theft Auto 5 created a major surge in PS3 and 360 sales, despite being exclusively available on aging hardware at the time. Major exclusives, like Halo 5 and Uncharted 4, still push a lot of hardware on their opening weeks alone. And games as minor (relatively speaking) as Persona 5 can cause hardware bumps.

Even Mario Kart 8 was one of these, seeing how its release seems to have been a major contributor to the Wii U's relative height in 2014 and 2015. Not to mention the Switch version, which is not doing much worse than Breath of the Wild.

That said, you will sometimes have games that seem to sell consoles, but aren't necessarily remembered well or played for long periods of time. See Titanfall and Watch Dogs.

I wanna see how Mario and Gran Turismo do this generation. They could be the highest selling exclusive titles for their respective console.

I don't think so. Nintendo has millions of hardcore fans that will but a system at launch irrespective of the library. The WiiU showed that. At the same time, Mario Kart 8 is on pace to outsell Breath of the Wild.

But, no, one game by itself cannot make a difference in this day and age on any platform.

Gt sport probably won't even outsell horizon, let alone Uncharted 4 and last of us II.

Forever and always, will a stand out title be able to shake the earth.

But wii sports.

in all seriousness, killer app doesnt mean that its the only game you play. It just means it the defining game for buying that system. I'm pretty sure the concept of a killer app originally came from computers, where they'd literally have applications used to sell their hardware (or firmware i guess). That doesn't mean that someone who bought an old computer for MS Word only used Word, but it would still be a killer app. Even the structure of the title implied that there are non-killer apps in tandem with it. The killer app can easily stand on a foundation of support apps.

Well I'd still strongly say that Pokémon was one of the biggest factors that allowed the 3DS to be quite successful in the time of smartphones. 

And Switch compared to Wii U launch month sales showed the exact opposite. Essepically when you look at the fact the Wii U launch library was actually one of biggest for any console.

Here are the first week sales for Switch, Wii U, Xbox One and PS4:

Can you spot the difference?

You're not wrong, to be fair though the PS4 was supply constrained and only launched in the U.S. I believe at the time of 1 million sales.

Well my point wasn't that Switch is above everything else, that turned around quite quickly with PS4, just that Wii U's numbers are extremely lacking compared to everything else. So clearly Nintendo doesn't have this magnitude of fans who will go out and buy whatever product has the Nintendo brand on regardless of how good it actually is or what games are on it.

Switch was a product deserving of high sales and it got high sales, Wii U was a product deserving of low sales and it got low sales.

With Nintendo, yes. Think the take up on early Switch would have been as high if not for Zelda?