The only thing that makes Itachi some trouble for Madara is: It is an ethereal weapon with an enchanted blade capable of sealing the target it pierces. Those who are stabbed by the sword are drawn into the jar and trapped in a genjutsu-like "world of drunken dreams" for all eternity. Itachi was able to use the sword to completely remove the Cursed Seal of Heaven from Sasuke Uchiha when he extracted Orochimaru from Sasuke's body and sealed him in the sword, and was also able to remove Nagato's soul from his body after Kabuto used the Summoning: Impure World Reincarnation to control him.
It can also cut through objects like a normal blade, thereby giving the wielder great versatility in his attacks. Being a variant of the Sword of Kusanagi, this sword can cut through almost anything, as seen when Itachi easily decapitated seven of Orochimaru's eight-headed snake form. Zetsu stated that Orochimaru sought the sword for all his life but could never find it.[2]
Along with the Yata Mirror, the Sword of Totsuka is a weapon wielded by Itachi's Susanoo, with the gourd being held by a second hand growing from its right forearm, while the actual blade is wielded by its right, foremost hand. Black Zetsu claimed that, together, these two weapons made Itachi's Susanoo invincible.[3]
The Yata Mirror was an ethereal shield with no set form or properties and has the power to alter every one of its attributes. By doing so, it can be used to negate any attack, whether it be spiritual or physical.[2] As such, it is said that the Yata Mirror has been endowed with all nature transformations, changing its nature to nullify all incoming attacks.
And Amaterasu: Amaterasu produces black flames at the focal point of the user's vision.[3] In most situations, this makes Amaterasu impossible to avoid. However, techniques of extreme speed allow the avoidance or interception of the jutsu after it has been cast.[4][5] Once created, the flames will not stop burning until their target is completely incinerated. The flames cannot be extinguished with water, the passage of time or any other normal methods;[6] only the user can put the flames out.[7] Said to be "the fires from hell" and to burn as hot as the sun itself,[1] Amaterasu burns any material — other flames included — until nothing but ash remains.[8] Throughout the series some objects have shown some degree of imperviousness to the flames such as Gaara's chakra-infused sand,[9] and Naruto's Version 1 chakra cloak.[10]
Amaterasu does not ordinarily require hand seals to be performed, though Sasuke Uchiha once used the Tiger hand seal, which is common for fire techniques.[11] This technique can also be sealed within the Sharingan of another person.[12] Beyond mere offence, Amaterasu's flames can be used as a deterrent, with users surrounding themselves in its flames to discourage physical attacks.[13]
Use of this technique puts a great deal of strain on the user, usually causing their eyes to bleed. Though the user can make Amaterasu incinerate things near instantly when focusing on it, Amaterasu burns fairly slowly normally, allowing targets to remove burning clothes before their body is caught ablaze or, if it's too late for that, remove the burning body part(s) before it spreads.[14] Other defensive options are pushing the flames away,[15] absorbing them,[16] certain space–time ninjutsu,[17] or being the jinchūriki of the Ten-Tails.[18] While impractical as a defense, Amaterasu can also be sealed.
Beware though, because both Tsukuyomi and Amaterasu use vast amounts of chakra, combined with his terminal illness, multiple use of the Mangekyō's abilities in a short period of time is particularly debilitating for Itachi, such that after using it three times in one day, he was required to deactivate even his normal Sharingan to conserve energy.[12]
Madara has: Huge terrifying amount of Chakra, Powerful Susasoo, Eternal Mangekyou Sharingan (chakra draining is reduced to an unnoticeably minimal level), better than Itachi in battle experience. We won't include Madara with Kurama since that will end it too soon. His ninjutsu level is the highest a ninja can ever achieve. Madara's mangekyou sharingan abilities are unknown. Madara obviously is physically stronger than Itachi. He has Gunbai Uchiwa, which can:
By utilising the Gunbai Uchiwa to block an incoming attack, the user nullifies the effects of the attack by converting the incoming chakra into Wind nature transformation, which is then reflected. As this reflection of an attack occurs both suddenly and unexpectedly, the reflected attack can prove difficult for opponents to evade.[1]
The user waves their gunbai as a fan to create powerful gusts of wind, strong enough to blow away several enemies in one swing.
Both can use Izanami and Izanagi, so there's no upper hand here.
Put in mind, Madara is so experienced that he can fight without even looking. So if Tsukuyomi is what we think will defeat Madara, it'll be hard. Even if he fell in one, particularly skilled Sharingan users can actually break free of Tsukuyomi's influence. We all know Madara is the most skilled among them. Madara will obviously know about amaterasu, it may be too late, or he may react quick enough to have it catch his armour and not his head and just take off the armour. Madara would win if he knows what abilities Itachi has. But by just seeing the jar of the Totsuka he will immediately try to dodge it. Yata mirror isn't much of a trouble, you can simply wait until Itachi runs out of chakra. Due to Itachi's small amount of chakra, he isn't able to form a perfect susanoo, which Madara is able to. Itachi will run out of chakra after using 4-5 of his abilities, while Madara hasn't even started sweating.
I actually came here to say that Itachi can defeat Madara. But after searching a lot and reading, I, declare, it's the opposite.
I really don't know how to imagine the battle, I believe Madara would crush Itachi easily. Remember, we are talking about The Ghost of The Uchiha!