Do we refer to Nintendo in the singular or plural?

It should be either "Nintendo is."

It's a single company. The fact that it employs multiple people doesn't change that fact that it is still, just one. If you mean the subsidiaries, then, you specify.

Singular. Nintendo is the name of a thing. Just like we say 'Microsoft is' or 'Sony is'.

イギリスの英語とアメリカの英語の中で、二つともは大丈夫です。

Nintendo [ ] above grammar rules.

tech it is "is"

but we do see peopel say is and are, I probably am one of them people myself haha.

Damn you for making me realize how rusty I have gotten in Japanese since summer started. Damn you to hell.

*Rips up study abroad application*

Neither.

Nintendo U

Organizations are grammatically OK to refer to with either the plural (as they are a collection of people) or singular (as they are a single organization), though it's more common to refer to them in the singular.

I imagine "Nintendo are" is supposed to make the people that work for them feel like they are part of a bigger thing.

I'll go with "Nintendo are" since it's nice to make people feel good sometimes.