Are we talking all time? Because there is more then one... But if you're talking recent I think they're kind of lacking but I would say Mario Maker is one of their coolest most recent games. In all time I would have to say something in the Zelda series though.

Super smash bros Melee, Legend of Zelda OOT, Wind Waker and Twilight princess

Even though I'm a huge Pokemon nerd, I got to give Metroid Prime has one of the best Nintendo games in my opinion. I know it's always argued Majora's Mask or Ocarina of Time is the best Zelda and/or best Nintendo game out there, but Metroid Prime was the best for me. It was honestly breath taking getting to play a whole new 3D world in first person, from a game that was side purely side scrolling. The graphics were damn good for the GameCube, the music was stunning, some of bosses were a challenge and actually made you think on how to attack it, and it all still kept the feel of the original Metroid games. That claustrophobic feel of you're on your own, having to collect items, enemies at every turn, lots of puzzles to solve, some that you can't even do until you get further in the game and come back, having to be quick in the head with quick reflexes for a lot of places, lots of lore about the game, lots of enemy lore to collect. I've always loved Metroid, but when Metroid Prime 1 came out, my GameCube's power block literally died from being on constantly from much playing that game as much as I did. Prime 2 was just as good as 1, way more challenging and actually took me a while, but my god was it worth it all. Prime 3, was pretty good, I wasn't too fond of it at the start, but mid-way that's when things started kicking up. Now, years later, I'm still waiting for a Prime 4, because Retro Studies did an amazing job on the Prime series and I honestly hope they make a return on the Nintendo NX with Prime 4.

There isn't. That would defy many laws or the whole universe, and upset the gods so much that Playstation will port the Five Nights At Freddy's series and sell the desk plushies for £2 each, then Xbox will revolt and begin to make Bungie sell exotic weapons for £3, then Nintendo will realise that they need to make their online services paid, and we will all be in a hell of the gaming industry falling apart, YouTube will shut down and then we will all have to resort to buying android tablets and phones, because there will be no more free apps on the app store, and we will all be sad because android is so bad