The team loses horribly. There is a reason someone like him is part of the akatasuki. First, the team have no knowledge of what he is capable of. Secondly, Kakuza is far stronger then any of these guys and taking out the sound four would be no problem for him. Haku is the same even if he used the crystal mirrors and only Zabuza is the only problem that would pose to him.
However, Kakashi dealt with Zabuza in his weaker form. Kakuza easily kicked Kakashi dozens of feet into a giant tree with just a simple kick. Killing Zabuza would be no problem.