Kisame loses first, wins second. He may even win first high diff.
In second, the brother's weapons become pretty much useless except for banana fan.
Scenario 2
1 Brother has cursing rope(rope of clarity), while the other has cutting sword(seven star sword). Without them together, they can't sucessfully curse, and only kiinkaku's banana fan is the useful sage weapon. Without their sage weapon, they don't stand a chance against kisame. Kisame raped base, V1 and V2 bee before even going into water dome. They'd lose individually and be ripped apart in water dome - that's if kisame even decides to use WD as he is fully capable of beating them without it. they've not shown near bee's speed, therefore kisame would be able to easily react to them as he was able to react to a V1 bee who is as fast as a V1 Ay. Because of that, if they ever decide to cloak, the cloak would be easily samehade ddrained. Add to the fact that kisame can mass shark bomb them when they're in base and it's clear kisame rapes. The 1000 shark bombs kisame made without samehade would be nothing on the amount of water shark bombs he's going to create with their tasty kyuubi chakra.
Kisame wins scenario 2 low-mid diff
Scenario 1
Really, Kisame can win this with intel. With intel he'd know to stay far away from them and only send in water clones and shark bombs. Even if he is cursed by the whip, he still has a chance as all he has to do is avoid the sword. Kisame isn't exactly slow, and seeing as darui was
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to injure them and dodge weapons for a while, kisame should have no major trouble in parrying them. For that matter, all their hits would be directed at Samehade since it is kisame's attack and defence, and I
Highly doubt that samehade can be cursed. Because of this, even if kin and gin get in close on kisame, he has the potential to take them on and drain away chakra from any techniques they use then movee away to a mid-long range. Because of the scale and power of his jutsu, he should be able to easily hold them off at range. Kisame always starts off with water shockwave, so the fight is guaranteed to take place on a body of water, and seeing as it's 2 strong opponents that kisame has no reserves about killing, he has no reason not to summon sharks(kuchiyose no jutsu). His summoned sharks along with water shark bombs, water jutsu and his high speed water movement, would prove to be too overwhelming for even king and gin and their banana fan. Kin and gin are close ranged fighters, but kisame is a mid ranged fighter. Because of this, there are very low odds that they'd ever curse him, and this is the essence of their tactics. If kisame decides to go into WD, it's all over for them. Even if they happen to curse him (he'd have to come within taijutsu range) they'd already be drained of all the chakra and on the brink of death. They'd be dead long before the 'silence' rule of the sealing gourd kicked in.
With intel, Kisame wins scenario 1 mid-high diff.
Without intel, He can still possibly win high-extreme diff, but he'd most likely lose high diff as he is more likely to slip up not knowing about their forbidden sage weapons.