I think with the 400 meter starting distance, team two has the immediate advantage. Deidara can deploy two clay birds; one carrying Deidara and Kisame, while the other carries Nendo Bunshin versions of the two. Kisame can also deploy a few Mizu Bunshins, which'll all utilize Subteranean Voyage, and make their advance underground.
Sasori and/or Itachi will either remain on the ground or engage in an aerial battle.
If they remain on ground level, they're getting destroyed. Kisame with his massive chakra reserves can use Hidden Mist from the sky that will completely engulf the entire battlefield, as his Mizu Bunshins then utilize Bakusui Shōha by partly surfacing from underground. As quick and formidable as Itachi is, while blinded from the mist, he isn't going to have an easy time dealing with simultaneous aerial and below the surface assaults - where Susano'o completely fails at shielding him from. And the same applies for Sasori. The Mizu Bunshins (all equipped with Samehada) can sense his location and will thus will be able to effectively utilize their suiton shark variants, and ability to absorb chakra. Meaning, Itachi (and any of his bunshins) has to constantly avoid getting bombarded from underneath his feet, as well as avoid the Mizu Bunshins stripping away his Susano'o's chakra (if being used). All of Itachi's counter suiton efforts are meaningless due to the Samehada clones. Then if we add the aerial assaults from both Deidara and the real Kisame into the equation... C1 (or C2), Daikodan, etc. I'm going to have to say my homie Itachi is getting wrecked.
In a more likely scenario, where Sasori and Itachi are lifted into the air and engage in aerial combat; they're still blinded by the Hidden Mist with less sufficient means of aerial capabilities. All the while, Kisame can sense out their location with Samehada and inform Deidara of such. Also, the thick mist should actively and progressively be ridding Sasori's laced IS of it's poision, making it much less of a threat. Given full intel, that should be Kisames aim anyways - washing all the poison away with his suiton techniques. Now, what are Itachi and Sasori doing here to win? They're completely blinded and Deidara has Nendo Bunshins flying around as well to make matters even more complicated. While actively focusing on and relying on Samehada's sensing, nothing team one does should go unnoticed. They're offense is practically nulled in this scenario. Genjutsu isn't a threat. Amaterasu/Katon variants/Magnatamas are absorbed, and/or healed from. And IS lacking it's poison, is hardly a threat with Kisame's healing capabilites being factored. Of course, this would be assuming any of it even lands under these conditions.
The only thing formidable is team 1's defense. Between IS and Susano'o... that's tough to get around, but luckily team 2 has the GSB. It will devour through both Susano'o (at the right angle, avoding Yata) and the IS shield. And to completely avoid the 3rd Kazekage converts his chakra into magnetism argument; Deidara continuiously bombards the sand with his clay bombs. That'll definitely eventually make it's way through. Kisame can also fuel Deidara with chakra to make his bombs even stronger. Not to mention, Hidden Mist+C4 is a terrifying combo. If Itachi doesn't actively keep his Susano'o activated, he's getting GG'd easily. Then we have the WD... Yeah, don't see how Team 1 is winning this.
Edited the stipulations. We're not seriously claiming that Totsuka is sealing Kisame's suiton, are we?
