1) Itachi said that Tobi is Madara. And Itachi is never wrong. Check
2) Kisame saw Madara's face. Confirmed Tobi as Madara later. Check
3) Kyubi recognized Tobi 16 years ago. Madara was the only one who controlled kyubi. Check
4) Tobi participated in uchiha massacre and said he had grudge on Uchiha. Only Madara had a reason to slaughter Uchiha. Obito killing Uchiha made no sense. Check
5) Human flesh in Obito's hand while his entire right side consists of Zetsu goo. Check
6) Madara talking to Obito's arm. Check
7) Tobi using izanagi multiple times(saving himself from Ama and Konan) while Obito had no idea about Izanagi. Check
8) Tobi acting exactly like Madara despite the fact that he had no reason to pretend to be him while no one was around him. Check
9) Madara called Obito "another Madara". Check.
Tobidara is true.
Black Zetsu is a parasitic character. He inhabits the body of those he chooses and influences them to do his will. Hes been doing this for centuries manipulating people and the shinobi system to create a prime environment and circumstances for Kaguya's return. Even after her revival, he inhabited her body in order to influence her as well.
Here are just some of the reasons why Zetsu is the counter to your points.
1: Itachi had no idea what Madara or Obito's chakra looked or felt like prior to meeting tobi, so he wouldn't know. However even if he did, It is likely that the chakra felt by Itachi was created by Zetsu's that he mistook for Madara's because Zetsu can duplicate chakra and characteristics of anyone. (proven by Kisame vs. Killer Bee fight)
2: It was never proved what face he saw. Just that he saw a sharingan and obito's mask. I believe that Kisame had previously met black zetsu (since he manipulates many people), not obito, and sensed black zetsu in control. This is why he placed so much trust in him later down the road.
3: While madara may have been the only one confirmed to control the kyubi, he certainly wasn't the only person who potentially could, nor the only person the Kyubi might recognize. The kyubi has lived for centuries and used to be a part of the Juubi, and when separated was friends with the sage. He likely sensed a chakra presence from a long time ago (Kaguya era) that he recognized. I have a strong feeling that Black Zetsu was influencing the attack on the leaf and is the one who "actually" controlled the Kyuubi. Since it is unconfirmed who exactly black zetsu is, he may have well sensed Hamura or the chakra of someone in the Ootsuki family.
4: This may have been a calculated move from Black Zetsu inhabiting Obito's body to rid the world of the Uchiha. (potential people who could stop his plan while collecting sharingans) While Obito may have executed the plan believing it was his own will, Zetsu influenced his ideals and decisions.
5: Correct, aiding the point that zetsu's cells are firmly implanted in Obito making him easier to manipulate.
6: Correct, Madara already knew that Zetsu was inhabiting Obito's body because he placed the cells in him. Creating a fail-safe incase Obito didn't follow the plan. (proved by madara forcing obito to revive him)
7: Zetsu is well aware of the sharingan capabilities, not only due to Madara using it to escape Hashirama, but prior eras of the uchiha abusing the power. Zetsu/Obito collected many sharingan for the very purpose of keeping a "Izanagi" eye ready at all times to avoid ruining the plan to revive Kaguya.
8: While he may have not had a specific reason to alter his character while he was alone, it does not mean that he needed to revert back. It is likely a Jutsu of sorts that alters his appearance, voice, chakra, and demeanor. By not letting his guard down he was less susceptible to attack and others discovering who he really is.
9: Madara at this time thought Black Zetsu was an extention of his will. (Just as Black Zetsu made him believe, proven in recent chapters). So at any time Madara thought black zetsu could be controlled at his will to do his bidding. By having "Madaras will" imbedded in Obito, one could say he is "another Madara".