I don't think they can render Hiraishin useless. Firstly, whether Kisame creates a dome or not can be rendered useless by using Gamayuda in conjunction with fire (e.g. explosive tag in this case) that either Kichi or Bunta use, which 'mixes' itself with water and evaporates it when ignited. We have already seen that water and oil is the weakness of Gaara's sand, and they cannot react to that speed combined with sensing and Hiraishin. What is even worse, is that these are basic techniques. Minato still has HM and Tobirama has his Edo Tensei. Ultimately both are tagged and killed with either a Senpō: Rasengan or kunai. First team stands no chance, whatsoever.
A katon is not going to evaporate a suiton of that size, even if enhanced by oil. (were you inspired by that one Part 1 filler episode where Naruto threw a paper tag into Gamabunta's oil to set it on fire and evaporate the sea monster? Lol)
Toad oil disables sand, true, but Minato doesn't know that sand is weak to oil so the only reason this could happen is if by chance.
Edos can be sealed by Gaara or drained of chakra with Daikodan.
Gaara isn't getting marked due to several reasons:
-Sand can't be marked due to it being composed of millions of tiny grains, which can be seperated rendering the marking obsolete
-FTG kunai can't penetrate Gaara's ultimate defense so Minato can't teleport past it
-He can also simply "catch" the kunai with his sand and then bury them underground so Minato can't teleport to them
-Due to his sand armour, he can "shed off" any markings if Minato or Tobirama do somehow get close enough to mark him
Kisame isn't getting marked either:
-FTG Kunai can't really be thrown underwater, they can just sink to the bottom (sharks can also swallow the kunai so if they teleport to them they teleport inside the belly of a shark)
-Water can't be marked due to it being liquid so Minato/Tobirama has no way to get to Kisame other than swimming, in which Kisame is far superior
If Kisame DOES get marked, it's not much of a problem
-To mark Kisame, Minato or Tobirama would have to physically touch him. At this point in the battle Kisame is undoubtedly fused with Samehada so just touching him to mark him means that they would lose chakra upon physical contact
-Then to teleport back to him, they have to touch him again. Which would make them lose more chakra.
-Unless Minato/Tobirama happen to go for Kisame's head, any wounds they inflict on Kisame are healed by Samehada, so a FTG slash doesn't kill Kisame. At this point Kisame can coubterattack by merking them with bones coming out of his body and stabbing them (he actually has displayed this ability, similar to Kimimaro).
add this on top of the fact that Samehada is a sensor and when merged Kisame will inmediately know Minato/Tobirama's location the instant they teleport + boss summons get merked by 1000 sharks, drained with GSB, or crushed/sealed by sand, I see very little possibility of Minato and Tobirama winning.
