The most damning evidence that Sidious was scared of Yoda comes from the little green Jedi himself: “If so powerful you are…why leave?” The only real answer at this point is because Yoda does indeed intimidate Darth Sidious.
He understood he lost the ethereal battle before their physical fight even began. Thus, Palpatine never viewed Yoda as a major concern, even though the Jedi Master fought him to a de facto draw during the events of Revenge of the Sith.
In Star Wars lore, the Fermata Cage is indeed an ancient Sith device that currently holds another Sith Lord. Palpatine sees this Sith as his rival and the only true threat to his galactic empire.
Sidious concealed his nature. Yoda sensed that the Dark Side was focused on the Jedi Order, but he didn't recognize Sidious until it was too late. The clearest demonstration of Sidious's skill is the fact that he dealt in person with Jedi Masters for 20 years and they never realized what he was.
Some incredibly powerful Jedi like Yoda, Mace Windu, and Obi-Wan Kenobi failed to realize what he was. For whatever reason, none of these Jedi could sense that Palpatine was the Sith Lord they'd be searching for.
Why Yoda TERRIFIED Sidious In their Duel in Revenge of the Sith - Star Wars Explained
Why didn't Yoda warn the Jedi?
As for the evidence that came later, Yoda believed that the Jedi had already lost by participating in the Clone Wars. He wanted to prevent Order 66, but he also feared what would happen if the Jedi gave into fear over visions of the future. Still, it's unclear whether Yoda was right to ignore the warning.
Master Yoda knew that Darth Vader was once Anakin Skywalker - the boy he sensed too much fear in to train way back in Star Wars: Episode I - The Phantom Menace. For many years it's been assumed Master Yoda was aware from the day Vader gained his cybernetic enhancements and signature wheeze.
Years after his death, during her duel with Jacen Solo, Lumiya alluded to Palpatine, saying he was a "psychopath consumed by power.". Palpatine's manipulative behaviour cannot be exaggerated as he manipulated the entire galaxy into doing his bidding.
Though Yoda and Qui-Gon respected each other, they were often at odds due to their differing beliefs; Yoda looked to the future while Qui-Gon lived in the moment.
Sidious himself felt that he and his peers had outgrown the use of lightsabers, and only continued carrying them to mock the Jedi. He ultimately viewed his own lightsabers as little more than an affectation, and rarely wielded them in combat.
So it's his entire life.” We'll see Dooku as a Padawan with his master, Yoda, adventuring with his best friend Sifo-Dyas -- who would later take the fall for the creation of the clone army -- and his time with his own Padawan learners.
As Darth Vader, he was one of the strongest beings in the entire galaxy. But even then, he was never able to surpass his master, Darth Sidious. A Sith Apprentice can only become the master when they murder the one who trained them.
Yoda had to shoulder that decision for years. However, he ultimately understood the importance of life, and the power he could have used to defeat Dooku would have been much better used to preserve two lives. Over the years, Dooku would commit countless atrocities and also suffer incredibly embarrassing defeats.
Windu has created and fully mastered Vaapad, a variant of Form VII. Yoda mastered the original variant known as Juyo. Both of them were able to fight with Palpatine on equal ground, matching him blow for blow. It is stated that Yoda beat Mace in a sparring match.
Star Wars Explained - A long time ago, in a galaxy far, far, away... Why didn't Yoda train Anakin Skywalker if he really thought that he was "the chosen one"? Yoda didn't want Anakin trained. He considered him to be dangerous, full of fear which could potentially be catastrophic.
Most viewers have forgotten that Palpatine seems to have been afraid of Yoda in Star Wars: Episode III - Revenge of the Sith - and even tried to flee from their duel.
