Should I make up a gaming console or could I use existing game consoles for a story? Would people like Nintendo claim copyright?
There's no copyright in the name Nintendo. You're talking about a trademark. Making references to popular culture in fiction, including references to trademarks, is generally fine. If you have the Nintendo electrocute a character because of a product design defect, and the work does well enough to get on people's radar, you might get a letter.
Typically, yes. There's no trademark infringement issue to worry about. If you portray the Wii U as a dangerous device that somehow causes death or dismemberment or other horrible things to happen to its owner, then you're closer to something that is problematic and would be better off inventing a name. But if your character just happens to be playing a Wii U, that's fine.
Don't do it! In fact while you're at it avoid mentioning food products, cars, oh my ...even countries might get offended if something bad happens there in your book. And do not write about John. I made that mistake once, and never again! He loves to write angry letters. Hehe sorry only joking. Yes it is fine. Ok back to watching my Samsung TV (other products are available)
And I'm off to play Fallout 3 on my X-Box 360 before watching Daredevil (the TV series) on Netflix on my Samsung TV.
As others have said, it is fine. Same goes for sports teams, TV shows, books, films, whatever... as long as you are just mentioning them and not saying that they are dangerous or somehow deficient. That could be construed as slander or something of the sort. I remember Rowling mentioned a Playstation in one of the earlier Potter books and I only remember it because I'm sure she had written it into a time where the Playstation didn't yet exist.
OFF-TOPIC: The PlayStation was released circa 1994. By the year 2000, when Rowling mentioned the PlayStation in the fourth book, the PlayStation 2 was released or was about to be released. But yeah, in the fourth book, Harry wrote to Sirius that Dudley bought a PlayStation and a fictional game that Rowling made up. Got so furious with it that he chucked them both out the window. What's interesting was that the fourth book is set in 1994. The PlayStation 1 wouldn't reach the UK until around September 1995. So, what, did Vernon make a trip to Japan without us knowing, bought a PlayStation 1 and somehow figured out how to make it work with UK wiring?? But yeah, mentioning it is fine. If she had Harry go, '...which, if you want my personal opinion, is the most evilest thing on the planet. A corruption of mental health', or whatever, Rowling probably would've received a cease and desist letter from Sony. EDIT: I agree with @Sweetness11 . It's better to make up a video game console, that way you can bash on it to your heart's content and not worry about the company giving you crap about it.
You could make one up - that way it won't appear to be anachronistic if the machine didn't exist in the time your story is set. It could be a parody of an existing machine, such as the "PlaySphere", "Fun Box" or "Titan 128".
That's what I meant when I said she had "written it into a time where it did not yet exist" - I was talking about in the HP-universe, not in real life lol. EDIT: Of course it did exist, but I had read about that Playstation mistake (that it wasn't available in the UK) and that's what I was referencing earlier.