Change my mind.

Smash should win.

Well Smash would be the third franchise to go beyond previous highs on Switch.  Mario Odyssey is already preparing to pass Galaxy and Breath of the Wild has passed previous Zeldas.  And of course Splatoon 2 also far surpassed Splatoon 1.  So Smash doing the same wouldn't be unusual.  20mil is a bit high I think but 15 to 17 is entirely within reach.  

Pokemok Lets Go just lacks some of the key selling points of main entries but the biggest issue is that it isn't Gen 8.  It's been shown time and time again that millions of fans don't care for third versions, gen sequels, and remasters.  So at best that will almost certainly limit it.  Anywhere from 5 mil to 12 mil I would say is the range.  I lean towards the middle.

And Gen 8 is confirmed for next year,.  Smash, on the other hand, will almost certainly not get a sequel on Switch.  

But you are pretending this is a core pokemon game. It is not. It's a side Pokemon game made to try to pull some of the success of Pokemon Go but without the main feature of Pokemon Go - walking around outside to catch pokemon. Like I said, it's gonna sell great no doubt, I think it could sell 10 million, but that's not 50% less than usual, because their hasn't been a side pokemon game like this before, so it is new terriroty. It's not like the core games and its not like the other non-core games like stadium and whatnot, so it is hard to know where it will end up but the best guess is between the sales of a core pokemon game and the non-core pokemon games that have been coming out on consoles since the n64. Usually the final gen or two of Pokemon on a system (I think they normally release 4 gens per system) are down to like 6 or 7 million sales, and I think that is a good guess for this since it is a side game, though with all of Nintendo's games selling gangbusters on the Switch I think it is possible it could see 10 million.

The core pokemon game is expected next year, that is the game you are talking about. You're confusing Pokemon Let's Go with the "real" Pokemon game next year. Yes I do expect the first full Pokemon game next year to sell crazy numbers and very possibly be the best selling game on the Switch.

"Sure, if a new Pokemon arrives quickly after this one but no other Smash" - I'm not sure why you doubt a real pokemon game is coming since it has already been announced, and I'm not sure why you think that there could possibly be another Smash when there is only ever one Smash per system. Your statement there agrees that Smash will sell better so why are you arguing against it given that both those things you say "if" about we already know to be true?

And as far as Smash selling the best ever, I don't think there is any question of that. The Wii had that massive non-gamer crowd and Smash was a little too hard core for the Wii audience since it is a fighting game, whereas you had games like Just Dance that regularly sold 7 to 10 million, but Smash only sold like 13 million, and then a more casual friendly Mario Kart sold like 36 million. The Switch audience is different and should pick up Smash at a much higher attach rate. Furthermore there hasn't been a single AAA game on the Switch since Mario last October, and Pokemon being a side game, Smash comes as the first major core Nintendo franchise game on the Switch in 14 months! It is the game that everyone on the Switch has been looking forward to this year. It will have insane sales and is gonna have crazy legs. The hype for it I think is bigger than ever before. We are over three months away from its release and it is already the best selling game of the year on Amazon.

Will keepnadding as it goes. Keep up the predictions

I am not so sure on Let's go reaching 15 million anymore, but Smash will still blast past 20 million

Super Smash no doubt

Smash bros

I'm going to go with Pokémon Let's Go...
If Pokémon Let's Go takes off, I could see Nintendo picking it up as another regular series, marketing it to kids and cell phone gamers and leaving the traditional Pokémon titles for longtime fans of the series...
I hope this happens so that we don't have to sit through any more tutorials at the beginning of the game...

You expect gamefreak to make the regular series more hardcore? If let's go starts to become it's own series, then we would have casual vs even more casual games.

Smash