Itachi's stamina "problems"...

[Multiply]

My boy was there for those 3 days and 3 nights pouring his chakra to seal the beasts and that takes quiet a lot of out of even shinobi's with hugh reserves

Not going to enter into this, 'debate', but actually the sealing method did not tax them that much. If you read back, Kisame and Itachi both used a clone technique to throw off team kakashi while they did the sealing. Also, it's not that much chakra because it's being split through all of them. Their chakra will come back faster than the statue is taxing them, or the taxation is not very high, if it lasts 3 days.

 

[Itachi Edo]

No lie, but having Minato back is a great make up for Itachi. Both used actual wits and not just out the air and plot power ups like Naruto and Sasuke.

 

[Itachi Edo]

Kishi had something special with Itachi. You say genjutsu the first name that pops in your head is Itachi. That in itself says a lot.