lelz I have some time to kill, I'll bite.
Zabuza v Mei: If Zabuza starts with Hidden Mist Technique then Mei starts with Acid Mist technique. Zabuza's mist now becomes inhabitable to him. And reasonably if she has a hidden mist technique she has a way to find him in said technique. But that's neither here nor there as Zabuza won't be in the mist anyway. Now that Hidden Mist and CQC is taken out of the equation, it comes to who has better mid to long range attacks. If Zabuza tries to do Water Dragon Jutsu Mei could easily block with Water Encampment Pillar, and then fire a Water Dragon of her own in direct succession. But this isn't necessary as it takes Zabuza 44 handseals to perform Water Dragon Jutsu and Mei only one. He wouldn't even be near being able to complete the handseals before he were blasted away. Additionally, Zabuza has to watch out for Mei's Lava style. Mei completely stomps Zabuza. There is nothing he can even try to do against her.
Zabuza vs. Tsunade: If Zabuza uses the hidden mist technique Tsunade can do one of three things to negate this technique (which should tell you now he's screwed) First off she could use her heightened sense of hearing, which she used to hear Orochimaru's heartbeat from several meters away in order to avoid being surprised by Zabuza, and to locate Zabuza once's he's close in the mist kill him. Second she could easily push away the mist with the resultant force from her striking the ground. Leaving Zabuza completely exposed. Third she could simply rise above the mist by summoning Katsuyu (who can sense chakra) at which point if Katsuyu comes out it becomes a stomp.
Now, dealing with Zabuza's CQC. Tsunade has a blast range that would fodderize Zabuza should he try to engage in CQC, but assuming that is not the method she goes with, then since you enjoy the databook so much Tsunade has a better taijutsu score than Zabuza, she'd outmaneuver him and kill him. For instance, because Zabuza uses a large sword his swings take longer and are far more telegraphed. She could easily avoid said linear attacks and hit Zabuza which is game over. At that point, she could literally disarm Zabuza, in the same fashion she did Naruto. Now the only possible problem for Tsunade comes in the form of Water Prison. But because Kakashi couldn't move means nothing for Tsunade because Tsunade's strength is several tiers above Kakashi's. And even if she couldn't move, Water is a conductor of Electricity, and in order to hold the water prison Zabuza must keep his hand in the prison leaving himself exposed to Tsunade turning her chakra into Electricity, and sending it through Zabuza's body screwing his nervous system. And considering Kakashi could still move his jaw to talk while in the water prison then Tsunade should be able to move a host of other muscles. Tsunade at most mid diffs Zabuza, if not low diff.
Zabuza vs Ay: Ay would probably have the hardest time as he has no way of finding Zabuza in the mist, that said so long as Ay's raiton cloak is up, Zabuza has now way of harming Ay, maybe water dragon jutsu will do some damage but it would be a far cry from killing Ay. Alternatively, Ay could zoom out of the mist, or go V2 and strike Zabuza just as the mist is beginning to form. Zabuza's CQC against Ay? lol Ay mid diff max
Zabuza vs Oonoki: Zabuza uses hidden Mist Jutsu, Oonoki counters with Moving Earth Core and now Zabuza's in the plain open. Oonoki creates an Earth Golem and Rock Clone to keep Zabuza busy and whilst fighting the golem Oonoki blasts him away with Jinton.
Oonoki Stomps