Well, let's be honest with ourselves here... Neither Lee nor Gai are quiet and Zabuza's silent killing in the mist is second to none.. He'd easily feel them out with a few Mizu Bunshin and then strike one of them down.
Meanwhile, Kisame just relaxes in the water as the Chinamen get killed.
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They ain't silent cuz they have nothing to hide

Water clones? The ones got
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? Betch please.
And they can't react to something they can't see; as being among the best taijutsu users and speedsetters; something Sakura did: [
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] [
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]. Beych please.
Did you forgot Lee has muscle memory which would lead him to
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? Betch please.
Wasn't Gai using nunchuks even whe reacting things that is not in his line of vision: [
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] [
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]
Also; when Gai was pawning Kisame (twice; manga fact); didn't he blew away masses of water: [
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] [
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].
Wasn't Lee doing that when he was a kiddo, even for a smaller scale: [
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]; and doesn't he have similar aura when he is opening the 5th gate: [
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]
Mist again?
Mermaid men lose this battle.