Some Nintendo franchises are more popular than they were back in the day. Mario Kart has a huge following and so as 3D Mario games, we can deduce that from Mario Kart 7 and Mario 3D Land sales (plus the insanely huge numbers Mario Kart Wii currently has). Don't forget the "Wii" series (Wii Sports, Party, Resort, etc), which are also really popular. 

So no, comparing GC with Wii U doesn't make sense for some franchises. 

Also those 2 Pokemon games were spin off and not related to main series, and those never sell as well as the main entries in the series. 

4 Zelda games? Wind Waker, 4 Swords (which is technically not in the main series) and Twilight Princess (which the Wii version took all the spotlight), so there's 3 unless you want to count the Ocarina and Majora's mask remake. So basically there were only 2 Zelda games during the GC era (and 1 of them technically being a spin off)

Plenty Mario games which include only 2 big franchises (Mario Kart, 3D Mario), the rest are simple sports games and a RPG (which again don't sell as high as Kart or 3D Mario). Mario Party only got very popular (7m+ units sold) with the Wii and DS (the decrease of Mario Party 9 can be attributed to Nintendo pretty much killing the Wii, not the franchise popularity per se).

Get your facts right next time.

we'll never know

Sorry,but remake/spinoff still accounts for it being part of the franchise. A mario game is a mario game therefore it should have sold regardless.

Same with Zelda I don't care if it's a spin off or not it's still a Zelda game.

The games the GameCube had are not the same games we'll get on Wii U. This is a poor way to convey what I mean, so I'll use an example:

Mario Kart circa 2013 is not Mario Kart of ten years prior. Double Dash was before DS and Wii. The difference: Mario Kart 7 eclipsed Double Dash's lifetime sales in less than one year. It's a different series entirely from a sales perspective.

I think it's a safe bet to say it would have, simply because of how much more popular the Playstation brand was at the time.

I'm in a very foul mood (i did indeed remember my love-hate relationship with Monster Hunter, but not that it could inspire such murderous impulses in me), so i'll leave it at that you need to understand that all Mario and Zelda games are not created equally, and depart before i say something i'll regret

Except it really isn't in anything but name. Mario Kart plays nothing like Mario Galaxy, and the sales reflect this difference in gameplay.

True, there were more things going against the GC, like being a "kiddy" console and Yamauchi burning the bridge with 3rd parties. However, I still stand by what I say  and I think that the PS4 will stagger at launch without the help of new optical media.

This is an interesting topic. I've thought a lot about this.

Gamecube shouldn't have sold as poorly as it did. It had an incredible stable of classic Nintendo first part, pretty decent third party, a normal extremely comfortable controller, and to top it all off it was powerful. (and pretty damn cheap).

I attribute the Cube's failure to a couple things:

PS2 was dominating in a way that we will never see again. Seriously, PS2 killed everything in it's path. It more than doubled the combined totals of Dreamcast, Gamecube, and Xbox. WIth a system like that, there is not much room for anything else.

Cube had no DVD player, was a more fun design rather than mature. Purple.

Now why do I think that the Wii U won't be the same? A couple reasons:

It's got all the basic media capabilities of any other console. Blu Ray is not what DVD was for the PS2. Some people will see this as a viable option for a streaming box. (Netflix,Amazon, Hulu, Nintendo TV)

It will get some casual sales when the price drops. I think the casual crowd has for the most part moved on from Wii, but some of that 100 million Wii fanbase will migrate. I guarantee it. It won't be anything like the Wii, but I could see 10 million families/elderly/casuals picking up the console when the price drops.

There is no clear winner like the PS2. There really will never be another PS2-esque system. The reason for this, is that more and more gamers are buying more than one console. Back then it was much much more common to own just one console, and that console was the PS2.

Nintendo's franchises have continued to grow as well. Mario Kart is now much bigger than it was back then, as is Smash Bros. They also have NSMB which they didn't have, that sells consistently in the multi millions. 3D mario is also so much bigger now. Add backwards compatibility with the Wii, and Virtual console, and it's just obvious that Nintendo has a lot more content now.

The Wii U is struggling right now, but if it doesn't break 50 million, I will be shocked beyond belief.

Actually it had weak core exclusives (Think Halo:CE & Fable, DMC/FF/etc), was the worst looking consoles (purple? Really?), had the worst controller (it's always PS vs xbox, not xbox vs GC or PS vs GC) and had no DVD playback. It makes a lot of sense why it didn't do well.