Why is zinc sulfate needed in the construction of a daniell cell. It seems that because the zinc is getting oxidized and not reduced there is no need to have a solution of zinc sulfate as it will produced when the zinc is reduced. The sulfate ions would simply cross the salt bridge and balance out the charges.
Zinc sulfate is not needed. With any other neutral salt in its place, your cell will work just fine.
Without any salt at all, though, it will not work, since pure water is a poor conductor of electric current.