None of these are special powers. It's something Kishimoto never bothered to explain in regards to MS sealing itself as well. There are a few points to debunk this:
1- Uchiha clan made many sacrifices to learn the secrets of the Sharingan. That can only mean one thing: how to go beyond the original abilities that would in turn be transferred genetically.
2- Tsukuyomi and KA are just powerful Uchiha Genjutsus. Going by the first point's established logic, it isn't out of the world that the secrets were recorded in scrolls and then learned by people who had a natural aptitude for Genjutsu. Reading the secrets about the Sharingan would enhance the sharingan, allowing it for the feats not possible with the ordinary eye.
A good example would be Sasuke and Itachi. Despite the fact that his 3T Genjutsu is just as powerful as Itachi's, his MS genjutsu isn't and despite possessing Amaterasu, Itachi's control over it is zero. Why are two genetically related brothers so different then, when Sasuke naturally possesses the ability to even negate Itachi's genjutsu?
The answer would be because of the secrets learned and the light sacrifices made with Izanagi, which is why it's a Kinjutsu like Izanami.
3 - Kamui or Obito's Intangibility was a 2 Tomoe ability. Which further leads me to believe that all Uchiha Sharingans are capable of unlocking these secret abilities, but what is unlocked is solely dependent upon the stress situation. For example, Obito's right half was almost crushed, but the Sharingan created a defense situation to allow him to slip through so that it would save his life.
If he didn't have that ability genetically or the Sharingan didn't have the capacity for it, then it never would have happened. Which is further proven by the fact that his other eye doesn't have it - it simply mimics the warping aspect the other eye created to save Obito's life.
4 - Madara and Izuna were first within their own clan to unlock MS. Whether there were more clan members scattered around the world or not? We don't know. As I mentioned that the Sharingan has the capability to unlock its secrets and powers. All of these powers cannot simply be developed if it's not genetically possible for the eye to use them.
Madara and Izuna simply didn't know about Amaterasu and other mentioned abilities. Susano'o may be rare, but all it needs is double MS to unlock it. Madara had it, and Izuna didn't as it's a rare genetic ability.
It's also quite possible that these abilities are rare among people, and depending upon the situation, the Sharingan resonates on with the ability that is bound to save the users life, as it has happened countless times now to be ignored: Sharingan always unlocks itself with the power of insight in life threatening situations - or situations that involve immense grief.
I am afraid there is no such thing as a created ability. It would make no sense for Sharingan to create an ability for itself.
He's only ever been shown to possess Susano'o. If he had any other MS techniques, they would have been showcased.
Izuna, however, has been theorized to possess Enton due to Tobirama's recognition after seeing Sasuke's use of Kagutsuchi.
Not quite. Izuna and Madara were the first to awaken MS. That doesn't mean they were the only ones with MS at that time. Had it been Izuna's ability, Tobirama would have made a clear cut reference.
