@ Strict, there are four ways that shinobi's from the very beginning are shown how to anticipate an opponents move. Above, left, right and below.
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Minato does indeed have these options as well as behind and in front with the exception being below.
In the encounter vs EI, he was the first person after seeing the technique to try and anticipate where Minato would teleport next using his kunai's.
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He was wrong as it was on Bee's tentacle. Now, Bee must have knew that his tentacle has been marked and that is why regardless of him being marked managed to yes anticipate it as he already had a heads up. He came to the common conclusion that if minato was to teleport, he would go behind him as that is the blind spot, luckily he was right.
Apart from me showing scans of bee having his left hand on his knee and the next chapter (when Minato teleported), having moved his left hand behind him, says that he knew exactly what he was doing. To top it off, when an exclamation mark is used it usually means that person whom this exclamation mark points to is shocked/caught unaware. We see this explanation coming from the fodder next to bee and not bee himself which again states that, he did indeed know what was going and wasn't shocked at all. His actions and body language is clear for all to see.
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Likewise during the third world war he did something very similar to the fodder. Teleported behind them, before striking. He didn't strike the instant he teleported like the examples you have given. Maybe that something he used to do as these two examples are identical but also during that period of time (third world war).
You can also see the exclamation mark on the fodder in the bottom left hand corner.
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You are right once he teleports is very hard to counter with no heads up, but body movement not so much. In the two scans you showed when he appeared infront of obito, swinging of the arm is the body movement. Likewise when he appeared above obito, the downwards movement to land rasengan is obviously the body movement so regardless of the fact that he teleports instantly, he does require some form of body movement to strike.
As for the fight vs Tsunade and Sakura the reason i said mid diff is because, for a start his summons has been restrict so you are wrong there. Secondly, the knowledge that Tsunade has on the technique, but also the fact that both of them are medic ninja's, who have shown that they are not going to be easily killed and with his restrictions imposed on him, it will not be as simple as, tagging and hiraishin blitz to the head like some think. Especially not when katsuya isn't restricted for the medics and can split into as parts needed to equal minato's hiraishin kunai's.
It may end in low diff not because of the reasons you have given, but rather because Tsunade has already been marked by minato's bodyguards, so that saves him the trouble. If Minato can sense that there is already a mark on Tsunade, then she bites the dust first and Sakura is finger food