I feel that 3rd party is a losing battle for the Wii U.

Simply put the wii u is most peoples "other" console.

You buy it for exclusives and play multiplats on your more online accessible system ( xbox, PlayStation)

And people that only own a wii u , well they didn't buy it to play cod or ac

By the way, I dont think Nintendo will do it. I think what they want to do is make their next home console and handheld be the same (the console would run games in hd and max settings, the handheld not)
And that way they would make only one Mario Kart (not one for handheld and one for console), only one 3d mario, only one 2d mario, and they will be able to create, and they would be free to create many other new games then.

I think the mistake here is assuming that Nintendo's business model and aspirations can and should be anything like Sony or MS.

Nintendo's fortunes with any given system are largely tied to how many consoles they can sell.  The more consoles they sell, the larger user base they have to sell their extraordinarily popular franchises to, the more money they can make. Certainly they can make money from third party licensing fees but that is much less than what they make from their own games and in effect third parties are competition with their own titles. Other ways Nintendo can improve the bottom line is by spending less money on R+D, selling hardware at a profit and being efficient (frugal) with game production. These are things that Nintendo has historically been very good at and why the profit they earn (even in their lean years) is very high in relation to their number of employees. Remember Nintendo is only just over half the size of EA.

So with that said I think it is a mistake to assume (at least in this reality) that 3rd parties are a very significant part of the equation for Nintendo. Nintendo's primary driver is profit, not winning console generations, winning is just a means to an end.  If they have good profit but only sell half the console numbers of the competition, they don't really care, for Nintendo that's a win. Selling a hundred million consoles doesn't necessarily mean anything to them because  the amount of profit they might earn from third party licenses still wouldn't be enough to offset the losses/gains they can earn by simply having their own business in order i.e. efficient, low cost operations with an affordable product.

For third parties they equation is simpler, by far the biggest modifiable for them is (any) userbase, more userbase gives more potential sales and profit. They have fewer avenues to address profit than Nintendo does as both a software and hardware vendor.  There ideal situation for third parties hardware-wise is a single successful platform, so they can effectively make one game and sell to 100% of the userbase. PS2 (and PS1) was the closest and to this and is part of the reason why Sony has such a good relationship with third parties, EA and Ubisoft etc. would love to see another PS2-like success as it allows them to focus resources on a (almost) single target.

For them (third parties) to be an important part of the equation from Nintendo's perspective you literally need third party games driving sales of Nintendo systems above the rate that the system would be purchased if /mostly just Nintendo games were available (pretty much the current situation). This would require, at least, complete third party parity. If third parties are attracting a larger market to the console, that is good for Nintendo as it improves the install base and allows them to make significant money on licensing and sell more of their own games. 

We are so very very far from this situation now that I just don't ever see it happening, such a strong historical trend has been established I don't know how it will be broken. I think Nintendo is now begninng to think the same, but it's taken them a long time to reach the necessary level of realisation.   Nintendo can throw money at third parties all they like to improve the situation somewhat, but they can't get them all on board this way, it simply isn't cost efficient.  From Nintendo's perspective and the reasons highlighted above that money would be far better spent internally bolstering development, improviing efficiency etc. which is I think where Nintendo is currently focusing attention. They have much work to do in improving their output if they want to thrive on this approach and not the moderate Nintendo output/moderate third party output that has worked in the past.

Where does that leave the poor consumer? It leaves them having to buy multiple consoles if they want to get all games,  but that situation would still be the same even if Nintendo managed to get half the major third party games on board, a still lofty goal from where they presently are.

MS and Sony are in a bigger fight than Nintendo and have been willing to throw money at the problem for longer term gains by, for example, spending more money on hardware R+D, loss leading, paying for exclusives etc. They can to a greater extent rely on the fickle third parties because at the end of the day it is only a small part of their business and if the third parties let them down they have other businesses to fall back on. They can rely on a fundamentally different approach because they have fundamentally different drivers and have the ability/desire to take different risks from what Nintendo can.

I'll stop there.

Take a look at the PlayStation YouTube channel. They promote anything and everything coming to their system. Exclusive, multiplat and indie all get plenty of showtime.

Perhaps if third parties didn't put gimped versions of their games on Nintendo consoles, or leave out certain online modes, or DLC, etc.......

Perhaps if Nintendo actually promoted top 3rd party offerings the way Sony and M$ do, and didn't treat their own games like the be all, end all of their own console then they could cultivate a healthy userbase that doesn't just buy only Nintendo-made products.

But that would require Nintendo to A: spend some cash, and B: share the limelight with 3rd parties... and we all know neither of those things are going to happen.

You really cant blame 3rd parties or even expect them to care at this point. Titles like Street Fighter IV (3.90 PS3, 2.78m 360), Tekken 6 (2.65m PS3, 1.24m 360), Battlefield 4 (2.97m 360, 2.02m PS4, 1.42m x1, 2.83m PS3) and CoD: Ghosts (8.90m 360, 1.93m X1, 2.47m PS4, 8.20m PS3) sell so well on other platforms. Smaller titles like Naruto and Tales games usually hit north of 600K on one or both SKUs. More and more Japanese games are selling well on PC as well as evidenced by Street Fighter X Tekken, Metal Gear Solid V, King of Fighters, Dynasty Warriors and Naruto coming to Steam. These type of games usually fail to crack 300k on the WiiU . Really why should any company go out of their way to cater to a such as small base of customers who never seem to give a damn regardless. There really is no point. PS4 + XBox One + PC is were most devs will focus on this generation, that's all there is to it.

The quick answer is they don't.

They just work to facilitate 3rd party developers' possibilities for presenting their games in just as attractive a way as Nintendo's own. Both on shelves and online.

And Nintendo does this. Mario Club usually has many many suggestions for 3rd parties on how to make their games more distinct, even early in development sometimes, and sometimes they listen.

Make hardware that is close in performance & features to the competition.

Developers will port to a minor console if it's almost no extra work or compromise. GC was like that. Porting from PS2/Xbox to GC was easy. I did it for some games at the time.

Since Wii & Wii U Nintendo's systems are almost a generation apart from Sony & MS, and devs don't like that. It's not only about effort & cost, but also about developers being sick of developing on that older technology for diminishing return.

If Wii U was selling well they would make an effort even if they don't like it, but since Wii U sold like crap it made the choice very easy for developers to not bother.

Well, you can't really blame someone for not wanting to buy a late port, no? I mean, what's the point of doing that when you can just buy the versions that are already out? :S