(Let me say to you all that I've been eating my words about Nintendo since I got a 3DS. With that in mind, let's begin!)

I have a few things to back up my claim - probably.

First off, the release date: rumors point to 21 November. That places it - and its hype cycle - ready for the holiday season, all guns ablazing, haters be damned.  That means it'll be on the minds of anyone buying a Wii U considering the advertising. Plus, you still have the bundles to consider.

Then, I can point to the launch of Mario Kart 8, and how well it's been doing at this point. We're seeing it home in on a 40% attach rate on Wii U, which implies that the holidays may not have as big an impact on it relative to other games (seeing as a lot of Wii U owners own it by this point). Also, I expect the impact of SSB on sales to mirror what MK8 did, except amplified by the holidays.

Then, I can point to the 3DS version. The demo actually managed to turn some of my friends* off, and considering what's happened with the slide pad in Japan at this point, I can see people skipping the 3DS version entirely and waiting for it to come out on Wii U.

The 3DS version can and will compete with the Wii U version - it happens on multi-plats. But, we're seeing a supposedly inferior version of Smash on 3DS getting released prior to the definitive Smash on Wii U. (Plus, GCN controllers on Wii U.) Nintendo is probably trying to milk $100 (or $400, depending on whether you have a Wii U) from fans of Smash.

(I might actually be willing to bet on this, of all things.)

I'm gonna say no. MK has always been a bigger franchise.

So basically you are saying that SSB WiiU will have a much higher attach rate than MK8, which already is at 40%.

Nah.

Oh, crap. My laptop keyboard screwed up.

Meant end-2015, not end-2014, argh.

Nope. I really can't tell where this confidence comes from. The only time Smash sold more on the same console was barely on the GC. It's also available on 3DS where a lot of people will get their fill instead of buying for Wii U.
So pretty much everything says nope. And I do believe MK8 will have the better legs.

I would bet but that bet is just too easy that it wouldn't be fun.

Nope, you didnt really back up why you think so either. hell you kinda made your own point moot by bringing up 3DS version. So far 3ds versions of multiplat games have done better on 3ds DESPITE inferior quality (lego city and Sonic lost world) hell in the case of Lego city that game was bundled with WIi U for some time and still hasnt sold more. As long as teh game is servicable people will opt to stick to the 3ds version. Nope Smash is not as big as Kart not even close and its releasing after Kart.

If you are a Nintendo fan you don;t really want to see this. On N64 (sold pretty well) MK outsold Super Smash, on GC (sold bad) Super Smash outsold MK, on Wii (sold very well) MK outsold Super Smash.

So the take home message is when Super Smash outsells MK the console as a whole sells badly. OK there isn't really a solid pattern because Smash was a new IP on N64. But still the GC/Wii thing is interesting.

Smash doesn't appeal to as wide an audience as Mario kart. Its possible to outsell mk8 but not likely.

Oh, absolutely. I think Smash will be #1 selling Wii U game once the console has finished it's lifespan. I think it'll be similar to GameCube's software rankings. Smash, then Kart, then 3D Mario, then the rest. Wii U is very much a core-gamer, franchise sequel machine, much like GameCube was. There aren't a lot of cross-over or casual games like the Wii had, and even if there were, the audience interest simply isn't there any more.

Releasing Smash before Black Friday for Wii U will sort of force the system into a lot of gamer's hands, because it's difficult to say no to a new Smash Bros. for console. They only come around once every console generation, and they're one of the best four player local co-op games around.

No way.
Smash 3DS will suck the wind out of Smash Wii U's sails.
It will sell well, but it will never catch MK8.