One of the main reasons why Yoda would've won against Anakin is simply because he was far better trained than him. Yoda could see the moves his opponents were going to make before they made them; therefore, battling against Anakin would've put him at a far heavier advantage.
While it's not to say Skywalker wouldn't stand a chance, the duel between Yoda and Anakin would be close. In the end, though, Yoda would be the ultimate victor if he fought Anakin in Star Wars' Revenge of the Sith.
As stated in the other answers, Anakin had the potential to become far greater than Yoda. Anakin's midichlorian count was greater than any other force user ever.
Aside from agility and telekinesis, Yoda could absorb and redirect Force attacks, like lightning. Because of his higher understanding, he would easily overcome Darth Vader in a fight, though that doesn't mean it wouldn't be a difficult battle.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker. Galen was secretly trained as a Sith Lord apprentice to Vader, but returned to the light side and the Jedi.
Master Yoda has risen above all others to claim the top spot as the most powerful Jedi of all time and the true chosen one according to IGN's audience. He won pretty handily as well, as he was victorious in 89,756 of his 95,243 battles and had a win percentage of 94.2%.
Some time later, he faced the Sith Lord Darth Vader. Infil'a put up a fierce fight against Vader, almost killing him by throwing the already damaged Sith Lord off of a cliff. Despite severe damage to his suit, Vader survived the fall, and repaired himself with parts from Infil'a's droid, Arex.
More cunning and devious than all but the most attuned Force-sensitive beings, Darth Bane could more than likely defeat Yoda in a battle of both strength and wit.
In Revenge of the Sith, we again see Yoda in battle. He fights Darth Sidious in lightsaber combat and also through the Force as they battle onto the senate floor throwing chairs at each other. While Yoda holds his own in both of these fights, he doesn't win any of them. We never see the greatest of Jedi win a fight.
Most of them were just happy to last longer than 20 seconds against the Grandmaster, and bragged about it to their friends if they could.
Yoda had an incredibly strong connection to the Force, which granted him numerous Force abilities. During exile on the planet Dagobah, Yoda was able to see Jedi that were active through the Force; he could not see one that had forsaken the ways of the Jedi.
Immense Strength: Anakin utilized his Force powers to amplify his physical strength; this made him physically stronger then most, if not all other sentient beings. His cybernetic arm also allowed him additional strength to overpower others with greater ease.
Unwilling to see his son die, Vader gave his life to save Luke, thereby dying as Anakin Skywalker. Anakin ultimately fulfilled his role as the Chosen One and brought balance to the Force, fulfilling Qui-Gon Jinn's belief in the prophecy that foretold Anakin's destiny.
By the time of Episode 3; Anakin is in his prime, and already one of the Jedi Order's most powerful “masters” (although technically still a knight), just behind Obi-Wan, Windu, and Yoda. Maul wouldn't stand a chance. Anakin stomps.
The Sith Lord's powers were enough to overwhelm the Jedi and send him plummeting down to the depths of the senate chamber. Yet the battle wasn't a complete loss for Yoda, as Palpatine was just as overwhelmed and seemed to have taken the same level of beating. Yet still, Yoda saw the fight as a loss and took his leave.
The arrest of Darth Sidious in Star Wars: Episode III - Revenge of the Sith did not go to plan, but it may have if Yoda had remained on Coruscant.
As powerful as Darth Sidious may have been, it's easy to forget he actually seemed afraid of Master Yoda. As seen in Revenge of the Sith, Palpatine initially thought he could deal with the aged Jedi Master - and then, when Yoda proved able to counter the Sith Lord's Force lightning, he fled.
Jedi Master Yoda is the most powerful of them all. This should come as no surprise, as he was the head of the Jedi Order in the prequels and was revered for his abilities during the original trilogy. Yoda's power is unmatched and was a real threat to Darth Vader and the Imperials.
Star Wars Confirms Yoda Turned to the Dark Side - and Almost Became the Most Powerful Sith Lord. With the aid of Count Dooku, Yoda could have potentially destroyed the universe if he had gone to the dark side in Star Wars.
Sidious is also known as The Emperor of the Galactic Empire. He rose to power in the Senate as a Senator from Naboo and lived a double life as a Sith Lord. Sidious is extremely powerful and held very complex knowledge of techniques to master the dark side's force energy.
Truly, the most powerful Sith Lord was Darth Sidious, better known in his public persona of Chancellor (later Emperor) Palpatine. Through cunning and manipulation, Sidious killed his master to claim the mantle of Dark Lord of the Sith.
He slays Sidious and returns to Obi-Wan, begging for atonement by execution, only to be met with true forgiveness instead. But just as this fantasy Obi-Wan refuses to strike his former friend down, Vader refuses to turn his back on the dark.
At that moment, the one in which Vader screamed, "No!" in Revenge of the Sith, the Sith apprentice believed himself to be his own worst enemy. Vader hated himself. It likely only grew worse when Vader realized that Palpatine had absolutely played him.
Introduced in the first film in the original Star Wars trilogy, Governor Tarkin is the Grand Moff of the Galactic Empire and commander of the Death Star.