'That's a good one, isn't it/that?' -- Question Tag after Demonstratives

Regarding the question in the title, I think we should use it:

That's a good one, isn't it?

'Isn't that' is respectively rare in this position, but I'm not sure if it's incorrect.

My question is: should we always use it in the question tag instead of this or that?

Solution 1:

With This/That we use it in the question tag. So the usage of isn't it in the question tag is right.

When These/Those is used in the main sentence, the sentence requires They in the question tag. For Ex. These are good, aren't they?

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