In both cases, Dooku and Rey used Force lightning during painful or hatred-fueled moments, and while Maul certainly harbored anger throughout his story arc - particularly for Obi-Wan Kenobi - he never lost himself enough to spontaneously use Force lightning. But that doesn't mean he wasn't capable of doing so.
Mace Windu, with his lightsaber combat form Vaapad, could reflect the lightning back to its source with a "superconducting loop". It required tremendous effort on the reflector's part, however, as seen in Windu's battle with Palpatine; Windu was seemingly able to overcome Palpatine's lightning.
Dooku first used Force lightning at a young age. According to the audiobook, Dooku: Jedi Lost, he was once abducted for a Dark Side ritual, conjuring lightning to kill his captors and escape. Dooku went on to become one of the greatest Jedi masters, but his ability to use lightning was seemingly a natural talent.
Kylo demonstrably couldn't defeat Snoke directly, instead killing his master via deception. Kylo most likely never learned how to conjure Force lightning, which is considered an advanced skill for dark side users.
Grandmaster Yoda himself was capable of summoning force lightning in the form of Emerald Lightning. Shaak Ti utilized this Force power. Her killer, Galen Marek was an extremely skilled user of this Force power, even after his conversion to the light side.
Why Darth Maul was Deeply Ashamed of the Way Qui-Gon Died - IN-DEPTH ANALYSIS
Could Vader use Sith Lightning?
In the Revenge of the Sith Visual Dictionary, under Darth Vader, in the Data File, it says -"As a result of having artificial arms, Darth Vader will never be able to conjure Sith lightning-nor be invulnerable to it."- Thats probably why Vader suffered so much in Return of the Jedi.
Either way, while Vader can use most other Force abilities, Force Lightning needs to be channeled, and Vader's limbs are explicitly not connected to the Force. The Star Wars: Episode III - Revenge of the Sith Visual Dictionary confirms Darth Vader cannot use Force Lightning, and even suggests this is the reason why.
She and Kylo Ren were both trying to bring the transport to themselves with the Force, and in her anger, she accidentally unleashed lightning upon it, destroying the ship immediately.
After much meditation, Koon concluded that it would be wrong of him to ignore its power and that he should develop it into a useful technique. As requested by the Council, he recorded his experiences with the Force lightning that he dubbed "Electric Judgment" on the Great Holocron.
Anakin Skywalker's Chosen One Potential Was Permanently Stunted. The Darth Vader comic book series reveals that, while the eponymous Sith Lord was indeed capable of using Force Lightning, the electricity could potentially destroy his life-sustaining suit.
Having trained in the ways of the Force, Darth Maul was a formidable warrior strong with the dark side and possessed deadly skills in lightsaber combat.
Maul. Maul Force chokes Bo-Katan Kryze in a display of power. At the Death Watch camp on Zanbar, Maul proposed an alliance to their leader Pre Vizsla, telling him and his assembled soldiers that he can help Death Watch reclaim Mandalore and kill Kenobi.
The duel. Darth Vader defeats Darth Maul. The two Sith Lords engaged in a lightsaber duel, going through the volcano and onto a bridge situated over a river of lava, which collapsed, though they both survived and continued their battle.
Darth Vader acts like he doesn't even know C-3PO or R2D2. They were with him since he was a child. He did everything he could to forget his past. Also, his plating had been replaced many times, and protocol droids all look very similar.
That made sense because all of the Jedi that used a Force choke did so when they were afraid, angry or desperate. It was simply too easy of a path to reaching the dark side, so the Jedi consciously chose to avoid using the Force to choke their adversaries.
As a result, Palpatine's face changes in Star Wars: Episode III - Revenge of the Sith because his dark side-induced mask was broken by the Force Lightning rather than the Sith lord actually being disfigured by his own attack.
In both cases, Dooku and Rey used Force lightning during painful or hatred-fueled moments, and while Maul certainly harbored anger throughout his story arc - particularly for Obi-Wan Kenobi - he never lost himself enough to spontaneously use Force lightning. But that doesn't mean he wasn't capable of doing so.
Vader knew that he could never defeat Palpatine by himself (especially after his master bested him on Exegol as well), which is why he tried to recruit Luke to help overthrow him during the Empire Strikes Back. He may have not been able to overthrow the Emperor, but he could throw him over the railing to save his son.
Due to Vader's mechanical suit, he cannot interact with lightning under the pain of suffering malfunctions in the vital life support systems he uses. This is a rare problem for him to come up against, due to only other Sith commonly utilizing such a capability.
We know that Dooku has a wide use of Force abilities and in canon, we see Dooku being The only apprentice of Palpatine whom he taught or was able to learn Force Lightning.
Windu put his lightsaber between Palpatine and himself to block the lightning so it doesn't hit him. And yes, the other lightsaber users could just do what Mace Windu did.
It became seen as a gateway to the dark side, with some choosing to practice it in secret. Remarkably, Mace Windu is only one of a few Form VII users who didn't fall to the dark side thanks to his refining Juyo into Vaapad.
