These ones/those ones/the other ones

Solution 1:

You have it right: the plural of this one is these ones; of that one, those ones. Some prescriptivists have it that the word ones is somehow incorrect, but I can't really see why, as it comfortably fills a gap that nothing else quite can. Regardless, it is considered informal.

I agree that ones doesn't sound quite as good in a negative sentence—none of the other ones can easily be replaced with none of the others—but in the affirmative or interrogative it's just fine to my ear. Which ones do you want? is equivalent to the ambiguously numbered Which do you want?, but just as which one makes the sentence explicitly singular, which ones makes it explicitly plural. I can't think of a better way to do that.