I don't think it's possible to say that any particular person was more powerfull than another. I'd say Palpatine and Yoda were both equally powerfull. At the end of their contest, Palpatine was the one who was looking worried at the energy that Yoda was absorbing. The shockwave knocked them both over. When Yoda fell, he was unable to get a grip on anything, but when Palpatine fell, he fell against a railing which he used as a hand-hold to pull himself up. That was just pure luck (and story necessity) rather than skill on Palpatine's part, so I'd say that Palpatine and Yoda were equal in their power to each other. Palpatine said that Anakin would become more powerfull than either of them, but Obi-Wan put a stop to that when he cut Anakin's arm and legs off...
Sidious defeated Yoda and could have defeated Windu but was probably playing mind game 😖hifty: to get Anakin to join the dark side. Sidious was smart too since he avoided the detection of the jedi until he could put his plan in action. the jedi didn't even know who he was until the very end when it was already too late starwars