Minato didn't show to use Tajuu Kagebunshin no Jutsu; Kyuubi's Chakra isn't an excuse since he splits his own Chakra and thus weakens his moves.
And as for a bunch of clones doing a blitz.
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The more clones are made, the more chakra is wasted and the weaker they get, just as the Hiraishin gets more inefficient.
Furthermore, Minato didn't display the ability to use Tajuu Kagebunshin no Jutsu; Kyuubi's Chakra shouldn't be an excuse. Despite Karasu Bunshin waste much less Chakra by using the crows Chakra as a medium, no one would say Itachi is capable of using Tajuu Karasu Bunshin no Jutsu.
How do you want him to show Tajuu Kage Bunshin when without an arm he can't even form handseals? Concerning Tobirama's statement, he didn't said it in the *********** translation. He said
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with clones and he said it for a reason. Their opponent
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, something he noticed when
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used hiraishin on him earlier with his explosive bomb
Notice he says "He countered it
in that instant" It was an instant moment. Only that current Obito is beyond simply fast
Hiraishin with clones has never shown to be slow. Notice there is no difference between or after teleportation(smoke remains, Tobirama's position, and so on)
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Concerning the Tajuu kage bunshin argument you're wrong. You can create as much clones as you want as long as you've chakra for the creation since like you've said, it divides evenly your chakra among the clones
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The problem is not there. The problem is in your capacity to maintain them
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It's for that reason why even a tired Kakashi after a battle against Zabuza
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Managed to create more than 20clones
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But like he said himself, he couldn't have maintain them or do something consequent with them. It was only to fool them
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In the scenario of Kakashi's feat, let's say he has 1/100 of his chakra left and he made say 50 clones, the total chakra in each one would be 0.02/100. This is why Kakashi tried to bluff with the clones, if it actually came down to it Kakashi wouldn't be able fight effectively with any one of them. Not only that but with a chakra so close to zero, you can die very quickly depending on the efforts you make while/after using the technique, since when your chakra reach zero, you could die if you have no stamina left
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So you can create as much clone as you want, but depending on the amount of chakra in each clone, it's not only hard to maintain them, but you put yourself in a life or death situation if you overexert yourself. It's for that reason that this jutsu is not suited for people with little chakra, reason why those type of ninja usually use a limited amount of clone during fights in order not to get your chakra go to waste uselessly
If you use one clone, him and the original will have a half of chakra(50%)
If you make 2clones, it's split in 3, so roughly 33.33% of chakra for each
If you make 3clones, it's split in 4, so 25% of chakra for each
If you make 4clones, it's split in 5, so 10% of chakra for each
... and so on
It's for that reason that people with low stamina like Itachi never use plenty of clones, but with Minato having an almost unlimited chakra at his disposition he can use and maintain them when and how long he wants