xD this is a 1v1 fight manyes the forest's are indeed HUGE xd
but that doesnt mean every SINGLE kunai will get caught by them he can place them in a certain place where the forest wouldnt be able to reach it, saying the forest will catch every single kunai seal is just speculation.
this just speculation but its a possibility that minato knew about the 1st hokages forest and spores since he knew about tobirama's technique just a possibility tho.
and if minato finds him? well he can tell itachi/nagato where he is
or start forming a plan/strategy
ma and pa can be a potential factor in all of this too.
wasn't op asking which one would last the longest against edo madara?
1v1?