Windu wielded the form in numerous battles, especially in the Petranaki arena against bounty hunter Jango Fett, where his relentless use of Vaapad overpowered Fett. While dueling Darth Sidious in 19 BBY, The Sith Lord quickly brought down mace Windu's three Jedi companions.

Who mastered all 7 forms of lightsaber combat?

Darth Sidious was also one of the greatest and most skilled Sith swordmasters, as he has mastered all the seven lightsaber forms, all their stances and techniques and is capable of using each form equally effective ambidextrously.

What form did Windu use?

Form VII: Vaapad

The key architect of Vaapad was Jedi Master Mace Windu, who developed the form to address his weakness by controlling his inner darkness and channeling it into worthy ends.