Gaara wins,even if kisame traps him in a water dome,he can use sand hail/sand tsunami to mix in with the sand and kisame wont have a choice but to dissipate the water dome as he cant breathe anymore and gaara can control the sand inside the waterdome to attack him,kisame isnt that fast without fusing,the only chakra he can absorb is gourd sand but even then it becomes natural sand again and gaara can still manipulate it,his sand attacks are immensly quick and he can create a dessert in notime now,his sand can absorb all of kisame's water attacks while he simply uses another sand to attack while making even more sand,current gaara is too much for kisame.