a burning black sun.... that sounds convincing.....
but considering the fact that raikage's arm took like forever to burn down.... I doubt amaterasu itself will burn down chibaku tensei's core instantly...... and before it is burned down Itachi will already be trapped in there.
true the shared vision would be a problem for nagato/pain.... But it happened after....
I didn't see Petra path in action.... only saw it's face for a moment and that's it.
Susanoo is made of chakra, so it is absorbable.
and no, Susanoo is not lightning fast. Summoning it is lightning fast.
Prove of it?
Rewatch orochimaru yamata orochi vs susanoo fight.
During that fight susanoo seemed kinda like a heavy armored warrior..... Slow but strong.
Itachi>Nagato is not proven until Kishi makes a manga of Naruto's Dream Matches.
As for Naruto, KB and Itachi vs Nagato....... No one still knows if Itachi alone could have done it. Which in my opinion Kishi used all 3 of them for a reason.
For the end.
SILENCE.
EDIT:
TAIJUTSU: Nagato~we all saw how Nagato stopped KB 8 tailed form and Naruto KM, can Itachi do that?
GENJUTSU: Obviously Itachi
HANDSEALS: Nagato does not even need handseals.... NAGATO HANDS DOWN
NINJUTSU: Nagato
Stamina: Nagato
Strenght: Nagato
Intelligence: Itachi
Speed: Itachi, even though it has been proven Nagato can fly via Deva path, no idea why he hasn't.