Darkness or Light? Philosophy in Knights of the Old Republic.

Well, you might as well say that in terms of a duel, Yoda is weaker than Palpatine:D.
But it's interesting to think about what would happen if Yoda went to take out Anakin, and Obi-Wan took on Palpatine...
I think it's clear that Palpatine would have defeated Obi-Wan... But the situation with Yoda and Anakin is unclear (although it's clear that he would lose to the green friend in battle)).

Regarding the lightsaber battle, maybe he's not better, but I would say that Mace Windu is better than both Yoda and Palpatine in terms of lightsaber combat, but he has no Force abilities at all).
Yes - in the end, Luke Skywalker would never have learned about his Jedi abilities, and Palpatine would not have been thrown into the shaft on the Death Star))) However, given the intrigues that are not shown in the film, it is quite possible that without Vader, Palpatine would have been overthrown... by Moff Tarkin or Admiral Motti... or eventually Grand Admiral Thrawn))) There were many contenders for Palpatine's place, but besides Vader, Palpatine also had many other powerful allies, whose stories were only revealed in the expanded universe... This is the famous Grand Admiral Thrawn, Lumiya, viziers, and the personal guard... and much more, thanks to which Palpatine reigned in the galaxy as Emperor for a good 25 years...

P.S.: Why are you so sure that Obi-Wan had no chance of winning?
P.P.S.: And at the end of SW III, it was quite sad for the Jedi Masters, who can be said to have been "stabbed in the back" - only Yoda and Obi-Wan managed to survive...
Obi-Wan was just lucky, and Yoda... well, Yoda is very smart :D, in general, this moment also proves his wisdom.

It's as clear as day... Dooku was also Qui-Gon's teacher and therefore knew and possessed techniques and the Force at a level higher than Obi-Wan... at the level of Yoda or Palpatine...
Yes, but - a huge number survived (for readers of the expanded universe), dozens of Jedi resisted for many years, but almost all of them were later found and eliminated by Palpatine's Inquisitors... And immediately after the 3rd episode, a group of Jedi who were going to finish him off with false information were killed by Vader...