Were they were outselling everything over the holidays?

http://www.vgchartz.com/weekly/43093/Global/

Pretty much this.

Dude, it's Pokemon. When was the last time a big Pokemon RPG like this wasn't a huge success? If you look at the brand of Pokemon it doesn't really matter what the first impression is.

I expect a nice boost, 600k for the month it launches, then everything will be back to normal.  keep in mind 3ds was much cheaper as well.

Pokemon: Let's Go is about as much of a "remake" as the new FF VII remake is both of which aren't and are technically "reimagining" of the original titles and in pokemon's case it could be the start of a new series as previously mentioned ...

Rarely has a Pokemon spin-off sold in massive (think 5M+ units) quantities and the closest it recently got was Pokemon Mystery Dungeon for the DS and Pokemon spin-offs thereafter came nowhere near the fraction of selling like traditional Pokemon since then. It does help that Pokemon: Let's Go will have a closer feature set to the mainline series than Pokemon Stadium or Pokemon Mystery Dungeon did but perception will mean a lot in it's case if too many previous customers disregard it as the "successor" to the mainline franchise then those changes will act as a detriment against it considering the already high barrier to entry ... ($360)

We also don't know much the new Smash title itself on whether it's a full blown new successor or an enhanced rerelease with extra content and if it's the latter then it would noticeably dampen the the expectations which could potentially affect it's system selling power of which the appeal of the series itself already has a great amount of overlap with Nintendo's biggest IPs since it's advertised as an arcade fighter battle royale between their most recognizable icons ... (it's hardly believable that Smash has it's own largely independent fandom)

We also don't know the entire pricing strategy either and the lineup could change during E3 this year but the fact that the PS4 has been performing more strongly on NPD than the Switch has so far this year compared to last year (in spite of the fact that the PS4 lost to the Switch in most of the NPD reports yet still came out on top in the last quarter during last year) and will likely continue to do so throughout the summer would seem to indicate that it is the PS4 coming in with the advantage in momentum at least for North America when the holiday's come around ...

Switch does not have a clear definitive advantage against the PS4 this time around in North America so it will not be able to build up a sizable lead against it during the holidays or if it even will have a lead so the Switch would have to be highly dependent on it's growth this year in Japan (will be interesting if it will be able to keep up in July this year since last year during that month released with Splatoon 2 which nearly doubled the sales of that month) and Europe to have a shot at beating the PS4 this holiday quarter ...

Are you triying to be sarcastic with that question?

If they pull another BotW/SMO, they will lose like last year. They need to do better, and even a lot better to "dominate" like the OP asked.