boys' or boys's, which is common or natural?
These table are those boys's/boys's.

In the above sentence, which is natural or more common?

Are both correct, but one or them is more common, or only one is correct?

If boys's is correct, which sound of boys or boyses is correct?

Question

boys' or boys's, which is common or natural?
These table are those boys's/boys's.

In the above sentence, which is natural or more common?

Are both correct, but one or them is more common, or only one is correct?

If boys's is correct, which sound of boys or boyses is correct?

Answer

These tables belong to those boys.

That would be the way I would say what I think you are trying to say.
"Boys's" is never correct, "Boys'" can be correct, but would be uncommon. For instance, you could say "The boys' bicycles were by the fence", but one would probably just say "Their bicycles were by the fence"

Answer

The only correct form of the two forms you give is this :    boys'

This means that that the object in question belongs to two or more boys.

And no, 'boys's' is never correct.  A three-year old child might say it by mistake, but he or she will soon learn that it is wrong!

NB As I'm sure you realise, 'These table' is wrong....

Answer

You can say "That isn't my toy, it's the boys'." You would say it liike "boys". Hope this helps!