I don't consider Wii a fluke. Nintendo was clearly intending to go for that crowd and designed the system that way and removed it from direct competition. Sure we can say it was one hell of a gamble since no one had tried it before (or at least suceeded), but it wasn't an accident at all.
About DS, it sure is freak to see it doing over 150M while its competitor was like 80M, never happened before and probably won't again. But from what I remember Nintendo HH were increasing their userbase with each iteration and when DS changed the concept of their HH line it made everyone get one system and it done gangbuster.
That wasn't aimed directly at you, I was just pointing out that Nintendo gets accused of being lucky too.
Sony was 'lucky' in the sense that Nintendo and Sega were making huge errors in hindsight. That's not a slight on Sony. Sony had a better understanding of what customers wanted and deserved their success. You could argue that Sony was unlucky that MS entered the fray. PS3 probably would have outsold Wii worldwide if MS hadn't joined in.
DS- It shouldn't come as a surprise that making games more accessible and aiming them at a wider, underserved audience would result in success. Either Nintendo predicted what was coming, touchscreen/microphone/camera games being available on every device, or Steve Jobs gave them the heads-up to help him remove Sony out of the portable entertainment space that Sony had dominated for decades. The DS games that Nintendo came up with are re-appearing on Switch with local/online multiplayer, button/motion control and the big screen experience whereas Angry Birds and Flappy Bird are nowhere to be seen these days.
I wouldn't rule out Switch doing 150M+ while it's nearest competitor only does 80ish.
Don't Play Stationary 4 ever. Switch!