Itachi would win the whole shebang on this one. None of the other Akatsuki members have shown themselves to be capable of dealing attacks capable of mountain busting, save for Deidara, who has to literally kill himself to do so, and Konan, who exhausts her entire chakra supply for one attack that can be a hit or a miss. If either of those attack hits Itachi, then yeah, he's done for.
However, with the Yata mirror, he can block ANY attack coming towards him. With this, he would block Deidara's suicide bombing jutsu, and he can obviously dodge Karura like Sasuke did because he has sharingan.
Konan however, would be able to kill him unless he used a Genjutsu to redirect her attack. However, she would only be able to use that attack if she knew that Itachi was coming and had years to prepare, so she is easily batted off by a single Genjutsu and exploding clone.
Kisame would be tough, but he really has no defense against Tsukiyomi or even Amaterasu, which can even burn under water since it's literally 10 times hotter than the sun. Kisame would at best be able to dodge him briefly before getting killed fairly easily by another casual Genjutsu, and simply getting outclassed with Itachi's superior speed and strength, that Kisame has said even he is scared of on multiple occasions.
Sasori will be tricky, because he can only be killed by hitting his "heart", and can't suffer from anything besides chakra depletion. His water and fire jutsu's will surpass even Itachi's, but once he lands a solid strike on Sasori's heart, which he would obviously know is the only way to kill him, using his great speed again, he would just stab him in the heart, while effectively reading his movements and dodging his puppets. If Sakura could do it, Itachi could do it as an eight year old with his fully developed sharingan.
The toughest one here for Itachi to fight though would definitely be Kakazu. While Hidan is easily taken out with a single Genjutsu, as Itachi cuts him into pieces with his own scythe, Kakuzu has to be killed five times before he actually dies. Itachi would need to be able to fight off five S-class "ninja", each one being a master in a different ability. If Kakazu's wind and fire masks combined, they might overpower Itachi's fire style, and the lightning and water style would prove a great trouble as well. Kakazu has the greatest range of attacks in the Akatsuki save for Pain, so he would probably force Itachi to use Susano'o, if not at least Amaterasu. With Susano'o, I don't see Kakazu breaking Itachi's defense with anything he has, so Itachi would end up slashing all five of them, killing them ASAP.
If Zetsu was there, he would definitely be the easiest. It only takes one good fire jutsu to kill him, as demonstrated by Sasuke. However, if he prepared and mad 10,000 clones, Itachi get's swamped. The only chance he has then is reaping through them with Susano'o and Amaterasu while also shooting off Yasaka Magatama's, which would drain him in a matter of seconds. So, Itachi will win this unless Zetsu has his 10,000 clones.