Arguably the most common form of conflict is versus Other. In this particular conflict, there is someone else your protagonist must face off against. While some other forms can get away with not having an antagonist, that doesn’t work in a versus Other conflict.
With the versus Other conflict, you always have someone outside of the protagonist struggling against your protagonist. Be that you have a super villain struggling against his arch nemesis, a bank robber against police, versus other conflicts have to have an antagonist.
Keep in mind when using a versus Other that you also have to spend time on developing and motivating your antagonist.