Darth Vader 5

In Stan's Empire
Darth Vader 5 was created as a right-hand man for Commander Stan (the rhyme was unintentional). He was assigned to destroy Vader 3, since Vader 4 had failed to get the job done. He didn't have much luck at first: Vader 3 kept defeating him in battle. But when Palestine took over from Commander Stan, Vader 5 accidentally stumbled upon a path to victory over Vader 3.

In Palestine's Empire
Soon after Palestine defeated Stan in a duel and took control of the Empire, Vader 5 attacked the Rebel Base and battled Joe Skywalker. During the battle, Vader 5 got his hand stuck in a control panel and could not get it out. Lots of ion energy infected Vader5's systems, taking away most of his enhancements and neutralizing his quantum armour. Vader 5 was left at only the strength of the original Darth Vader, which led Joe Skywalker to eventually defeat him in battle. Vader 5's circuits were eventually fixed by his personal mechanic, so that no energy could ever rob him of his power again. He was upgraded with Beskar Armour, which was stronger than quantum armour. So now, not even a Death Star blast would be able to damage him. Vader 5, once he was upgraded, faced Vader 3 on the ruins of the Metal Planet. Vader 3 still had quantum armour and was thus vulnerable to the ion energy that Vader 5 transferred to him via his lightsaber. So Vader 3 was destroyed for the first time, but when he exploded, he damaged Vader 5's body, throwing him out into space and transferring the ion energy into his systems and overloading his ion shielding. So even though Vader 5 managed to transport himself to the Vader Head, he arrived there in pieces. While Vader 5 was repaired, Emperor Palestine was defeated in his 2nd duel with the Jedi. So Palestine's forces retreated to the Deep Core to fortify their last territories. Five years later, Vader 5 and Vader 3 faced each other, as Stan and Palestine battled. But while the Stan/Palestine battle ended with a fatality, the two Vaders were unable to destroy each other, thanks to holograms and their Beskar Armour. Once Stan declared peace with the Yeda Republic, the two Vaders made peace as well and helped hunt down the Renegades.