Tobirama wins.
-GKF causes massive damage, and is repeatable. 2 Edo's makes this even easier, due to the fact Tobirama can teleport to either one of the two and make it explode form both sides. It dwarfed Juubi clones by a large margin, which were larger than Bunta. It's not SS size, but nevertheless enormous.
-TBB has to be fired off into a direction. Tobirama simply teleports to a marking on the opposite side of where it was fired, and since the TBB never makes contact with its originating wielder unless prematurely exploded, it cannot possibly affect Tobirama on the opposite side.
-Tobirama's Suidanaha easily slices off tails when Hachibi's tail was cut off by a shuriken, which would never slice a Shinju tree branch.
- SM Rasengan affected the Juubi jin because it is composed of senjutsu. The analogy is flawed, a False Analogy. Senjutsu is the only thing that works on the Juubi jin, so the GKF having failed implies it is weaker is deemed idiotic. Or are people claiming because Senpo Rasengan damaged Juubito, Senpo Rasengan>TBB tree explosion, which was nullified by Gudo Dama [
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].
-Juubito being immune to chakra based jutsu=/=Hachibi immunity to chakra based jutsu.
-Hachibi loses all his tails from Suidanaha, is heavily damaged by GKF affecting his real body alone, with no tails to assist. At that point, he will simply be taking GKF's to the face while he cannot touch Tobirama.