Was Lucci one of the strongest characters in the world, such that it would necessitate a 2v1? Didn’t think so. So yes, it works. They are facing someone far stronger than Zoro is. That’s the end of the story.
As for them against King, they would do to him what Luffy would, destroy him. They’re fighting Big Mom, he is going to lose eventually against Zoro. It’s not close.