Are のだぞ、のさ、のだ grammatically wrong?

Question

I've been told の is formal, thus のです is grammatically right.
Yet, のだ is not.　Only んだ would be correct.

Therefore, 「んだぜ、んさ、んだぞ、んぜ、んぞ」 are correct and 「のだぜ、のだぞ、のさ、のぜ、のぞ」 are not.

Do you agree? Why or why not？

Answer 1

As for the difference between んだぜ/んだぞ and のだぜ/のだぞ, yes, the former is far more common, but the latter form is still grammatical and occasionally heard. A fictional pompous person may well talk like ～のだぜ/のだぞ with their close friends.

んぜ/んぞ/のぜ/のぞ do not exist.

• 見たんだぜ。見たんだぞ。: OK, informal male speech
• 見たのだぜ。見たのだぞ。: Less common. pompous and/or old-fashioned
• 見たんぜ。見たんぞ。見たのぜ。見たのぞ。: ungrammatical

I don't know why, but のさ is more common than んさ, and のよ is more common than んよ. んさ/んよ sounds a bit dialectal to me.

• 見たのさ。: OK, informal male speech
• 見たのよ。: OK, informal female speech
• 見たんさ。見たんよ。: dialectal