As a water player myself i prefer haku suigetsu and hinata hinata makes a * good tank haku acts as a barrier as well as good damage and suigetsu is a better version of zabuza. If you don't like hinata zabuza is a decent tank with his water clone. As for summons you need one that goes from knockdown to low float and have a chase that goes repulse to low float

i forget about zabuza, but what i think hes weaker version, with usless ninjustsu. right nkw i go with decent combo hits (max 6) with good survive ( iruka shield plus konan shield for herself) So i dont use him.

if u want to build up a great waterteam i can tell u some tricks. what u rly need is a ton of sealscrolls for kage tressure (lvl70)and every event that can give u tenten gnw. if ur lucky ull get chojuro or even mei. good chances that that u will drop ao in those 60 pulls for the rar. those ninjas will make water rly strong.
im not the biggest fan of neurotoxin for pvp unless u have godlike refine and chaos the whole team. u give up 40% dmg for that and often it gets cleansed right away. a weaker interupt from another ninja is good enough. i also use haku a lot. u can rly feel that 80% dmg buff.