It’s in the FAQ. Like with the other bad guy teams, if none are in play, the players must ensure nobody dies (typically achieved via circle vote) if they want to win.
So your options were everybody winning or everybody losing.
I thought if that question is done and the Oracle is in the center, everyone would retain their regular winning conditions, unless a role brings it from the center. It seems better and easy to go because there is a small chance you get the group in union if they are from opposing factions.