Key point being only for a few seconds. You don't know the intricacies of Dusk Crow. We've argued whether its obvious from the start or not. According to what we saw in the manga, it is. Minato would break it and teleport away from whatever Itachi brings. Itachi can't do much in that time.Itachi, Minato's summonings can be controlled continually by sharingan and put into situations in which he can kill them easily. Itach is already most likely aware of his ability maybe not version two, but Minato has 0 knowledge whatso ever about Itachi. Itachi, who is also versed in the art of fuinjutsu knows that you can place a seal on someone via touch, meaning he'll stay clear from any taijutsu battles with Minato, who he would know is an expert at fuinjutsu.... The deciding factor of this match without a doubt would be genjutsu, Not even going to argue whether Minato would make eye contact.. that will just turn into a never ending debate..... I will argue that Itachi doesn't need Tsukyomi to end this fight, and he can finish it off with his dusk crow ability.. which doesn't require handseals or eyecontact.. something like that will easily put Minato into a comatose state leaving his body susceptible for attack even if for a few seconds... it's an op and broken ability that people fail to take note of, and Minato has literally no counters to it considering he doesn't know of its existence.
As for the brawl between the characters.. once again Itachi would definitely have a general idea of the workings of FTG, as he had known intricate details of the hokages personal life, and has shown that he was quite the studious young lad.. Keeping a safe distance from the ground Kunai and utilizing his skill in shruikenjutsu to keep any ftg 2 kunai away from him as per norm would be the obvious method of defence .... With minato's speed and ability, it's obvious that the majority of itachi's seen ninjutsu and taijutsu would be the totally wrong approach.. He would just be wasting chakra shooting katons and water jutus, something Minato can easily dodge... and we all know Itachi isn't that stupid... The only option he has then on would be genjutsu, an attack you can't dodge...
Summonings on a whole are a bad idea, they are big and or slow and are all definitely incapable dodging an ability like amaterasu.. something which once again, Minato has no knowledge of, nor knows Itachi holds such a technique...
Heck even with a Sharingan genjutsu on A, Onoki had the time to make a golem and save the Raikage before any Susanoo could touch him.
The small window of opportunity is usually too small as shown in many instances in the manga. Example-when Shee genjutsu'd Sasuke. Suigetsu and Juugo could protect him before even V1 armor Raikage could touch him.
We also see when Itachi tried to attack Kurenai whilst she was under her own genjutsu. She broke free and dodged.
Even Itachi and Sasuke could break Kabuto's sound genjutsu in the manga before Kabuto could attack.
Shikamaru immediately broke Tayuya's genjutsu
When the genjutsu is breakable and obvious, it has never been effective In the manga so far.
Bee could break Itachi's Sharingan genjutsu in time.
Itachi's only option is trying to blitz Minato immediately. Probably not happening since all Minato has to do is form a hand seal to break the gen(it'll take Itachi longer to run at Minato than for Minato to form a single hand seal)
Itachi himself said it. A genjutsu which yyour opponent can escape is dangerous. Itachi might just get close to Minato only for Minato to break it and kill him due to close proximity. He can't prep Amaterasu in the time so that's no worry and as shown by Madara against A, Susanoo is slow as well. His best option would be to throw weapons or blitz Minato.
Weapons....Minato can break genj and disappear, heck Bee could break, bring out swords and counter!
Blitz....too dangerous, Minato could do what he did to Raikage; telepoert away leaving a kunai behind, teleport behind Itachi and kill 'em. Considering he'll be in the same situation as Obito and Raikage it would be impossible for him to activate Susanoo or dodge.