The "Wario Cup" is weekly because not even Wario would want to crunch enough to make it daily.
It won't just be playing against the house in the new WarioWare.
Nintendo released a new trailer for WarioWare: Get It Together which in addition to revealing the character roster, also showed off two new multiplayer modes. "Variety Pack" mode pits local players and their chosen WarioWare stars against each other in exclusive games, while the Wario Cup is a weekly-rotating online score challenge.
The trailer can be seen below: