What if the fight had been allowed to continue? Kurenai left to take Kakashi to safety but Asuma and Gai stayed back to handle Itachi and Kisame. Who ends up taking it?
Asuma's the weakest one here. He goes down easily to Kisame. 6 Gate+ gai is the real threat here, and since he' going to be fighting on the water and not look into Itachi's eyes, Itachi can't cast Tsukuyomi on him. Itachi either uses Ephemeral or Amaterasu before Guy can release the gates (which itachi can easily see coming) or a Susanoo to make sure that even if he releases to the gates, gai's attacks will be null.