He can't plant a rasengan in your face if you're not tagged and have blocked his kunai. Any jounin can react quickly enough to form a jutsu to then defend against him if does reach youYou have some good points.
You can prepare a defense
Yes, The best kind of defense for FTG is a static defense (lighting armor/susanoo)
Unless you have super quick reaction speed getting a jutsu off befor minato plants a rasegan in your face will be tough.
"You can anticipate
FTG requires hand seal(s) - so monitor his hands and react accordingly
He'd obviously attempt to teleport to the kunai closest to you"
Kinda of hard to anticipate, Also FTG doesn't require any hand seals.
You also think Minato would go for the obvious choice and teleport to the closest kunai knowing thats what his opponent will be expecting it because its the most obvious move.
Also he throws multiple kunai at once, You cannot stop them all, even if you try you are open for a counter attack.
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FTG does use hand seals, remember when Kakashi said that Madara's s/t technique exceeds that of the fourth's?
His hand seals will help you anticipate for an oncoming attack. And no jounin is dumb, they'd obviously know which kunai to react to when he teleports. That is if he can throw a kunai past you
That's why I've placed Nagashi or a jutsu of that nature as a requirement to fight off FTG. So he can't rasengan or kunai, you're always protected from his close range attacks