You obviously don't understand what I'm saying. If Minato can't get a FTG tag outside of Hashirama's Mokuton's radius in time, he's screwed. If he teleports back to his house or whatever (assuming OP hasn't restricted that), he loses by BFR. Other than that, he's not escaping miles of forests that are formed in seconds, even with FTG. And if Minato decides to do that and play a battle of attrition, he loses anyway.
It's like this: In the few seconds it takes Minato throw, let's say 20+ Kunai in an attempt to scatter them, Hashirama makes tons of Mokuton that crush the Kunai along with Minato.
Though i do see what your saying, i don't think you are seeing everything.
1. Minato does not only need kunai to teleport. He can tag seals on tree branches and teleport to them later.
2. Kunai are crated from steel/metal. I wasnt aware wood could crush steel.
3. He isnt only limited to rasengan and ftg, he also has frog summons that could help him get air borne long enought to spread kunai.
4. I dont think it will be too difficult for minato to escape mokuton tree world, becuase old hiruzen escaped it.
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Now i will agree that i cant see how minato would fatally injure hashirama (unless he seals him with uzamaki seal), but i cant see how hashirama would catch him.