Haku wins.
Water source or not, Haku shouldn't have any trouble evading Zabuza's Suiton techs given his speed and reflexes (which both inherently outclass Zabuza's). This is supported with feats like hopping in midway through Kakashi's Raikiri attack
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, which should be enough to react to/avoid any kind of Suiton tech Zabuza pumps out.
Kakashi was taking his time with this raikiri. His speed in using raikiri has been noted many times, even moving so quickly that someone as experienced Kakuzu was unable to hear or notice him. The manga even showed Kakashi moving with the raikiri, despite his ability to move with it at speeds so great that include matching Gai's punching in Asa Kujaku.
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And I'll just copy and paste my own post from the past explaining the raikiri/asa kujaku comparison:
EliteKakashi said:
I think you're mistaking at what I'm comparing here.
The comparison is Kakashi's foot speed in comparison to Gai's Asa Kujaku. I'm not comparing Kakashi's foot speed to Gai's foot speed in 6 Gates.
As your scans noted, Kakashi and Gai start their assaults(Gai's Asa Kujaku, Kakashi's Raiden) when they're back to back, started from the same point.
Gai stays stationary and uses Asa Kujaku on the acidic wave approaching him.
Kakashi launches forward to cut down the bijuu chakra arms with raiden.
He covers this distance:
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In the same amount of time that Gai creates barely any more "peacocks" from Asa Kujaku(top scan is him starting the technique, bottom scan is how many more he's shown to have created in the time that Kakashi closed the distance from Gai to cutting through those bijuu arms):
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What this shows is Kakashi can move roughly as fast with Raiden/raikiri as Gai can punch with Asa Kujaku. This is an impressive speed feat because Asa Kujaku is Gai simply moving his fists so quickly he can produce flames:
3rd Databook Asa Kujaku said:
With speed so high that the friction produces flames
So no, it's not Kakashi keeping up with 6th Gate Gai. It's Kakashi keeping up with the speed of Asa Kujaku, the "technique" itself.
So, while I'm not ignoring it as a speed feat, it's hardly as impressive as someone may want to make it out to be, seeing as if Kakashi was actually going full speed with it and didn't take his time, Zabuza would have been dead before Haku even thought about moving.
In terms of it being enough to evade Zabuza's suiton? Possibly so. I don't have much issue with that statement, although Zabuza himself(granted the same speed as Haku in the databook, 4, and while I understand the databook isn't the end all, be all of discussion, it's the only reference point we have to compare) couldn't evade his own(copied) technique, though this can be accredited to him being angered/confused by Kakashi's sharingan.
So to wrap this up, Haku probably could avoid the suitons, however, the raikiri intercepting feat isn't as impressive as simply saying "Haku managed to intercept Kakashi using raikiri at it's max speed".
CQC is Zabuza's only real advantage, and with a feat like
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, there's no reason he can't do the same against any of Zabuza's CQC-centric attacks, avoiding any detremental damage from his sword in the process.
Zabuza has the advantage of the mist and silent killing on top of the CQC. Haku having knowledge of it doesn't save him from it, considering Kakashi, with knowledge of it, and with a sharingan(which is the only thing that saved him from death, managing to block Zabuza's shuriken at the last second, Zabuza even notes it's impressive he managed that even with the sharingan)
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, was only barely able to react to Zabuza's attacks in the mist.
And we have no reference point for Haku's "reaction"(which still resulted in Haku getting hit pretty hard, would result in death from getting hit by a blade), as if I recall correctly, it wasn't shown where Gai or Lee came from in terms of the angle or if Haku saw them before hand.
Putting up the Mist shouldn't be an issue either, as Haku's senses, combined with superior speed/reflexes, should counteract any kind of advantage Zabuza would gain by putting the Mist up in the first place.
Haku should be able to put up the Crystal Ice Mirrors (takes a few seconds at most) and take the win there. Zabuza won't be able to destroy the mirrors, or at least not fast enough (Giant Cyclone requires lots of seals) before Haku starts cranking out attacks with Senbon at light-speed.
You're trying to tell me Haku has reaction feats on par with Sharingan Kakashi, who struggled greatly in the mist, having to rely on letting himself get slashed to win? Yeah..no.
Given Zabuza makes no noise in the mist and Haku is completely lacking of anything like the sharingan that would allow him to react last second to anything Zabuza does to him(which as I showed above, Kakashi had to rely on to save his life).
Combining Zabuza's mist with his bunshin abilities that fooled even Kakashi(and you might claim intel saves Haku here, but Kakashi had knowledge of Zabuza's bunshins too) and Haku is completely outclassed. On the extremely rare and off chance Zabuza gets caught in the mirrors(and you're going to have a hard time explaining to me how he would be caught), he simply shatters one of them with his sword and leaves, but again, with his bunshin abilities and knowledge of mirrors, the only thing that would ever get trapped by Haku is a mizu bunshin.
