.

In this way, is Vader stronger than Sidious?

Sidious is more powerful than Vader- in the suit. Anakin, pre-suit, had the potential to be twice as powerful as Yoda or Palpatine. Since Darth Vader is “more machine than man,” he lacked the amount of midichloriuans to adequately communicate to the Force, and so, was unable to become more powerful than Sidious.

Also Know, can Darth Vader beat Sidious? yes, vader is slow in his suit, but he adapted and is able to keep up with very agile opponents through force based physical augmentation. vader would kill sidious within 2 strikes, provided sidious was able to get his lightsaber in the way of vader's on the first strike.

Just so, how did Vader kill Palpatine?

Enraged, the Emperor attacks Luke with Force lightning. Unable to bear the sight of his son in pain, Vader, renouncing the dark side to become Anakin Skywalker again, throws the Emperor into the Death Star's reactor, killing him.

Did Vader ever fight Palpatine?

Vader never ever attacked Palpatine, he thought he had no chance against him alone. He was probably correct - Palpy was avid user of Sith lighting which doesn't go well with cyborgs as Vader. But that doesn't mean he never plotted against him.