Conditions for Susano'o Awakening

Itachi, "The one other Jutsu that took root in my eyes... once both Tsukuyomi and Amaterasu were awakened"

DBII, "There are two doujutsu the use of which is allowed exclusively to those who have awakened to the clairvoyant eyes of Heaven, the Mangekyou Sharingan: Amaterasu, which speaks of Light and the material world, and Tsukuyomi, symbolizing the spiritual world and Darkness**. Only in them who hold both of those, dwells the power of the wild, rampaging god... Susanoo."

Sasuke, "A power that only those who have awakened the Mangekyo in both eyes can achieve. The third power... the Susano'o"

Obito: "Sharingan that actually acquire the Susnano'o are rare... I like to stock good eyes.

Cnet:

Tobi: A Sharingan that can activate even Susanoo is a rarity... / I wouldn't want to let a nice pair of eyes like that slip through my fingers. // In fact, I wanted to give him the opportunity to train them up further in combat with the Five Kages... / It was I who sent him here. // I would have liked to have him weaken you to the point where I could take you hostage, as well... / ...but it looks like that was too much to expect.