The Tag Wiki for the nintendo tag describes its usage as follows:
Use this tag for questions about the company or about multiple consoles/handhelds; for questions about a single console or device, use that tag instead (e.g. nes for questions about the NES).
Although I have no problem with the first usage, questions about Nintendo, I disagree with using it on questions which are "about multiple [Nintendo] consoles/handhelds". Adding the nintendo tag on questions about multiple consoles/handhelds doesn't add any useful information to the question, since Nintedo isn't relevant to the question at hand (at least no more than they would be on questions about one nintendo console).
An example question is the following: Is the Wii U compatible with Gamecube games?
This question isn't about Nintendo, and so that tag doesn't add any useful information.
However, there are some situations where I can see a need for a tag for Nintendo hardware, for example: Nintendo (SNES, N64, etc.) Cartridge Revisions
Now, to be honest I'm not 100% sure what to do with this. I do think the second usage of the tag should be removed, and an additional usage should be added which somehow encompasses questions like this one, which cover all of Nintendos consoles along with specific parts of their hardware (cartridges in this case), but exclude its usage on questions like this, where the question is about two specific consoles.
I think the key difference is when the tag is required to avoid overloading a question with a bunch of tags. Obviously we shouldn't tag this question with nes, snes, n64, ds, et cetera. That's just one giant mess of tags, and the scope of the question really goes beyond each of those tags/consoles.
What should we do with nintendo?