Here's how the battle goes down.
Minato: Hmmm...seems I've been brought from the belly of the Shinigami to entertain a bunch of bored Naruto fans by fighting Itachi.
Itachi: I finally died and these guys brought me back. Oh, well. Long time no see Minato. I remember when you and Kushina-san used to visit mother all the time. Then you guys died....then I killed mom.
Minato: why the f-uck would you do that?
Itachi: Cuz Danzo said so.
Minato: That mofo?! Wait, the rest of the Uchiha clan just let you do that?
Itachi: Umm....I sorta...killed them too.
Minato: De fuq?! You massacred your whole family?!
Itachi: well. Me and some masked dude who calls himself Madara.
Minato: You a-sshole. You idiot! He attacked Konoha with the Kyubi and made me seal myself for all eternity!!!
Itachi: Yeah...he told me. Sorry bout that.
Minato: and you still worked with him?!
Itachi: well, Uchiha wanted to destroy Konoha...they were gonna stage a coup. Your son Naruto could have died, he's lucky I got into Akatsuki and was being lazy about capturing him
Minato: Hmmm...no arguing with that...well, let's get a drink. You're above 20, right?
Itachi: Yeah, but alcohol kills man.
Minato: we're already dead. Come on, I'll take you to the best strip club in the afterlife.
Itachi: Yondaime! You're married!
Minato: don't worry, I sealed myself away and let Kushina die. She can't catch me now. Why do you think they call me genius? *winks*