Apart from Madara Uchiha, 9 has no chance. Sasuke, Madara is without a doubt the most powerful known Uchiha in the series' history. Madara was already considerably stronger than Obito, and the fact that his version of the Ten-tails was flawless further added to his might. Even if Tobi somehow managed to create an infinite number of clones with the same genjutsu as him, they would still be useless against someone who does not need their hands to fight. As for now, it is safe to say that Madara is strongest out of all of them. He was able to defeat both Sasuke and Hashirama simultaneously with little effort. Tobi is probably around his level right now. However, given time, Madara could easily become stronger than him. In conclusion, there is no way that Tobi can beat Madara unless someone else more powerful comes along. Even then, he wouldn't stand a chance.