If they were you would have seen more Wii U units sold.

Thiiiiiis!

big in what sense? sales? On 3DS, 2D & 3D Mario are each over 10 million. On Wii U, 2D & 3D Mario are each over 5 million.

as for Zelda, the series ranges but typically sells 3-5 million (Adventure of Link, Link to the Past, Link's Awakening, Majora's Mask, Oracle of Ages/Seasons, Wind Waker, Phantom Hourglass, Spirit Tracks, Skyward Sword), only a few have sold over or under that amount so the series is generally stable.

And marketing is crucial to selling either.  Given Nintendo's marketing for the first two and a half years either reached almost no one or made their product look about as appealing as oily rags look to people who are on fire, it's a miracle their console has sold the current numbers.  And given their resistance to bundling hits at or near launch, refusal to lower prices even as the market screams at them to do so, their insistence on only marketing games that already have sold enough with previous entries to not need it, I would say their games are doing pretty dang well.  I'm not saying Nintendo doesn't need to do more of certain things (Xenoblade needs FAR more marketing in the future, there needs to be a new Metroid with FAR more marketing, need to more aggressively push for certain franchises to be on their consoles (no true console MonHunsince 3 is a ridiculous missed opportunity)  etc etc), but the marketing disasters of this gen and late last gen by Nintendo cannot be overstated in terms of their impact.

There was a lot more affecting the Wii U's situation than just Nintendo's games. It has a proprietary gamepad that drove up costs to like 100$ more than what its hardware justified, and it uses a difficult architecture, limiting 3rd party support (not saying it would've gotten tremendously more if it had been x86, but it certainly would've helped). The Wii U could've at least sold in Gamecube territory if those issues had been fixed, and Gamecube-N64 territory is where Nintendo has been at after they lost their near complete third-party control from the NES/SNES days. The Wii was an anomaly, but if your definition for big is "Wii"-big, then yeah, I doubt Nintendo's games will ever be "Wii"-big again.

Also, despite the Wii U selling less than the Gamecube, the Wii U's bestselling game has sold more than the Gamecube's bestselling game, illustrating my point: Nintendo games are still big. Their hardware on the other hand...

Wait..... what?
Mario, Mario Kart, Pokemon, Super Smash Bros, Animal Crossing always sold (and continue to sell) crazy amounts of copies on its main iterations
Even with the small install base of the WiiU, Mario, Mario Kart and Smash passed the 04 million mark of physical copies sold. Pokemon X/Y; Pokemon Omega/Ruby and Animal Crossing on the 3ds are some of the biggest hits this generation (13, 10 and 8.8 million respectively)
Zelda, Donkey Kong, Pikmin and Fire Emblem are not as big in sales as those franchises, but still has respectable numbers, with all main games surpassing 01 million copies (02 million in the case of Zelda)
I don´t think such sucessful franchises could be considered irrelevant. BUT, I do agree that Nintendo has been having difficulty, for some time, to create new successfull IPs. Tomodachi Life and Splatoon are huge hits, but some experiences, like Steel Diver and Fossil Fighters, have not been promising.

Clone Sakurai and have him work on bringing life back into their games. Kid Icarus: Uprising was amzing despite how limited it was.
Give young talent a chance, JUST LOOK AT SPLATOON. Its well past Miyamoto's time and Nintendo need to move on.

^This

Well said.

Not every game needs to be a huge hit. A game like Steel Diver basically equates to a small downloadable title and even Fossil Fighters is the type of series that could transition into a sub-$20 download only series next generation. These types of games a small/niche support titles.

What? How did you reach that conclusion?

Kimishima has yet to prove himself, I got nothing against him. Aonuma has yet to make a Zelda game I like, he ruined my favourite franchise. Two very different things.