Well, I disagree with the part of sealing some of Madara's will into Obito.
Madara's plan in general (without Obito):
-give Nagato his Rinnegan
-use Zetsu to influence Nagato and convince him to his cause
-synchronizing Nagato with Gedo Mazou (he could because of the Rinnegan)
-Zetsu with Nagato gathering tailed beasts
-Zetsu somehow forcing Nagato to revive Madara (lol, good luck with that) and taking from Nagato the Rinnegan
When Obito came along, Madara thought he had convinced him, and plus Obito was also an Uchiha so Madara thought that Obito is a good addition and insurance to the plan because of his loss of Rin and all this crap about the world being evil. And in case Obito turned his back on Zetsu and Madara, he could be controlled by Zetsu because half his body was made from him. Also Obito with his MS would come in handy when attempting to retrieve the Rinnegan from alive Nagato if he would betray them. Plan after that:
-reviving Madara
-reviving Juubi
-Madara becomes its jinchuuriki
BOOM PLAN COMPLETED
Obito's plan:
-influence and control Nagato
-synchronizing him with Gedo Mazou
-sealing tailed beasts
-reviving Juubi
-becoming its jinchuuriki
-optional: taking Rinnegan from Nagato for himself
-puuting the world in Mugen Tsukuyomi
---All along keeping Zetsu informed that he ineed intends to resurrect Madara (he remembered that Zetsu owns allegiance only to Madara)
He never meant to revive Madara. You are forgetting how scared he was when he saw Madara in the coffin in the hands of Kabuto. He wasn't scared that the world will know he is not Madara but the fact that Madara can interfere in his own plans. Also, Obito made the whole world believe that he is Madara, Kisame and Itachi included.
Kisame just probably thought that only Madara would be able to control Yagura who was perfect jin. He was also convinced easily to Obito's cause because of his own reasoning (go see the chapter he had a flashback and died later on)
As for Itachi: only one Uchiha was known to be missing (Madara) and seeing some foreigner from outside of the clan and the village entering the Uchiha shrine for which you must be an Uchiha, Itachi must have thought about Madara and this was the only logical choice. You must also remember that Obito tried very hard to immerse himself in the role of being Madara.
Itachi knew about Madara's past from Obito and that is a fact. Remember who was telling the truth of founding Konoha after Sasuke killed Itachi? That's right, Obito himself so he must have told the same to Itachi as he was said to be his teacher later on.
MS techs are unique for closely related family (Sasuke and Itachi for example) it doesn't mean that Itachi was taught by Madara how to use Amaterasu or Susanoo. The eyes "awaken" those jutsus <-- Manga fact.
Obito feared Itachi's intelligence, because being close to him, Itachi was the only one actually discovering the truth of Obito not being Madara which would ruin the whole plan because Nagato would turn his back on him then.
Madara in Obito acting like a goofy guy... no, just no. Have you seen chapters from the moment he was revived? Does this Madara match the meaning of a word "goofy" to you?
In the chapter of Rin's death Obito returns to Madara, he explains him lots of stuff and teaches him some kinjutsu, then passes his will to create black Zetsu and then goes and dies. End of Madara in those times. No will or any other Madara's part in Obito.
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