The issue with Zabuza + Earth Main is that Zabuza's Mystery causes blindness to up to 8 non-water attribute ninja from either team. This means that every time you use Zabuza's Mystery, you are locking down at least one member of your team as well as any member of your opponent's team who is not water. The earth main's skills can amplify your team's attack numbers, but if they are non-water, they too will be locked down by Zabuza. Sadly, I've only seen Zabuza used on predominately Azure Fang based teams.