Wild card games are mostly only played in home games these days, so it's up to you to make the house rule. Occasionally I've played stud with wild cards where the more "natural" hand did prevail, and five of a kind beat straight flushes but not royal flushes or something. Up to you and the other players to decide that though.
And Syfted has it, BTW, there are some legit draw poker games
that use the joker as a wild card - usually standard draw or ace-five lowball. Don't know that they get played in many casinos
these days though, and they certainly haven't been played at the WSOP
in a good few years.