Kylo Ren's lightsaber form was something of a hybrid, which blended three styles together: Djem So, Juyo, and Niman. Djem So used an irregular reverse grip and was meant for practitioners who loved fighting with a more offensive edge - a perfect fit for Ren.
At first, Rey primarily fights with a lightsaber the same way she would have with her quarterstaff. However, after studying Luke's Jedi scripture and training with Leia, Rey probably uses Form VI: Niman, a jack-of-all-trades lightsaber form that combines different aspects of Forms I through V.
By performing a lengthy ritual with the lightsaber, a Mystic can draw some of its power into themselves for a time." This means Kylo Ren could have actually boosted his own dark side Force power by harnessing his lightsaber's cracked kyber crystal.
Vader's son, Luke Skywalker, learned Form V in part by mirroring the swordplay of his father in their first duel, and the younger Skywalker ultimately defeated his father with his use of Form V during their second duel.
Obi-Wan Kenobi used Form III.
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.
Through the Force, Yoda was considered to have mastered Form IV to its highest level. He used it in almost all of his battles, and his mastery of the style caused others to describe him as virtually unstoppable against most opponents, including Separatist battle droids, despite his small size and advanced age.
Mace specialized in the seventh form of lightsaber combat, AKA Juyo or Vaapad. Windu was the only known practitioner of this form that didn't fall to the Dark Side, mainly because the style calls for an aggressive, unpredictable approach (much like Maul's, just less jumping around).
For example, Dark Lord of the Sith Darth Bane wielded a curved-hilt lightsaber —a weapon traditionally associated with Form II.
For Ahsoka, lightsaber form is crucial because she's a dual wielder. While Jar'Kai is the method of dual wielding, Ahsoka Tano's lightsaber form is a variant of Form V, much like her master, Anakin Skywalker.
Even though Kylo Ren uses a red lightsaber, harnesses the dark side of the Force, and wears a cape, he is not a Sith. Because of that, he can never hold the title of Darth.
The lightsaber's redesign was a byproduct of the bleeding process that damaged its kyber crystal, rendering it dangerously flawed and unstable, and necessitating the lateral vents were meant to prevent the cracked kyber crystal from overloading.
Rey's lightsaber was a yellow-bladed lightsaber that was constructed by the Jedi Rey Skywalker following the First Order-Resistance War.
Leia Organa wielded a blue-color lightsaber during her year of training. Leia Organa's lightsaber was a blue-bladed lightsaber powered by a kyber crystal in the core of the hilt.
Skywalker lightsaber. Anakin Skywalker carried this blue-bladed Jedi weapon throughout the Clone Wars. After dueling his former apprentice on Mustafar, Obi-Wan Kenobi took Anakin's lightsaber and kept it on Tatooine for nearly two decades.
Seemingly abandoned by her parents on Jakku, Rey grew up a scavenger amid the wreckage of war. Her life changed when she agreed to help a droid on an urgent mission for the Resistance. Rey discovered she was powerful in the Force, and sought out the vanished Jedi Master Luke Skywalker to train her.
Form II relied on careful and controlled strikes instead of power and strength. Count Dooku was a master of this form and trained the Sith assassin Asajj Ventress in its use, though hers was less elegant than her master's. The Grand Inquisitor was a proficient Form II practitioner.
1 Darth Sidious
There has been no Sith, as powerful, meticulous, nor as evil as the Emperor himself, Darth Sidious. As previously mentioned, Sidious trained in the Dark Side by Darth Plagueis before Sidious killed Plagueis in his sleep, making Sidious a Sith Master.
The Force Unleashed's Starkiller is a practitioner of Form V, a defensive and opportunistic approach to using a lightsaber. There are seven forms in total, but some - including Form V - have multiple disciplines.
However, Maul was devoted to the physical aspect of Form VII, as the Sith sought a purely physical victory over any enemy no matter how numerous, but by the Clone Wars, Maul grew out of this, now incorporating the Force.
7 Form VII: Juyo (or Vaapad)
Consequently, Form VII was outright banned by the Jedi for a long time. However, Jedi Master Mace Windu took it upon himself to refine Juyo into an offshoot known as Vaapad: the perfection of Form VII. Windu developed Vaapad to control his inner darkness and channel it into worthy goals.
The Forbidden Forms were forms of lightsaber combat used by the Sith during the Sith Wars. According to the testimonies of the Jedi Cervil the Uncanny, lightwhips—a lightsaber variant with a flexible blade—were used to defend against Sith Lords who utilized the forms.
History. Practitioners of Form IV included Yoda, Qui-Gon Jinn, Aayla Secura, Ezra Bridger, the Grand Inquisitor, and Anakin Skywalker. Yoda was a master of Form IV.
Form I, also known as Shii-Cho, The Way of the Sarlacc, or The Determination Form, was the oldest and most rudimentary form of lightsaber combat developed by the Jedi Order and was taught to all members of the Jedi Order.
In fact, Yoda was trained in all seven forms of lightsaber combat and had full mastery and knowledge of all of them. He was considered to be the best instructor at the Jedi Temple when it came to lightsaber combat, knowing which forms were most appropriate for each of his students.