Based on what? All I hear your own headcanon without any source behind. While I am providing proofs that why there was no spirits, you are still insisting on your own headcanon. I still don't know what's the basis of those statues are being the Sith spirits. Why do you think we see them behind Rey? There is nothing behind her. Again, it's a baseless suggestion. Vader killed Sidious. And more importantly, Sidious has foreseen Vader's betrayal in RotJ according to TRoS Novel. And Sidious was prepared to escape to his own clone body, because that's all he could if Vader betrays them, and Sidious and the past spirits of Sith couldn't possess Luke's body, if Luke kills him as a Jedi. There was no such a thing. If your theory was correct, all Sidious could do was letting Vader to kill himself, or letting Luke to kill himself, then he could possess either Vader's body before mortally wounding Vader, or he could possess even a better body if he let Luke to kill himself. But he did none of it, just like he didn't do that when Ben Solo and Rey tried to kill him, he tried to kill them back, all he should do letting Rey to kill himself so he and spirits of the Sith could possess Rey's body. This is why what you're saying makes no sense. If the spirits of the Sith lords were actually exists, they would possess other Jedi bodies many times before instead of escaping to a broken, and dying Sidious's clone body which was rotten and crippled. Sidious and the past spirits of the Sith lords couldn't do that, which is why Sidious didn't let Vader or Luke to kill himself, because they were Jedi, and the Sith couldn't possess their body against their will. It's very simple really. So just like Sidious and the past sith lords couldn't possess Vader's or Luke's bodies, they couldn't possess Yoda's body as well. I understand you're trying to find excuses on why Yoda didn't beat Sidious, but your excuse really makes no sense. And it's already confirmed that Sidious can't do that when a Jedi kills him, which happened twice (killing Sidious), and they didn't do that twice. Yoda simply couldn't defeat Sidious, because Sidious was more powerful than he could deal with. Sidious is the guy who is more powerful than people like Maul, Dooku and even Vader, so Yoda's failure to defeat Sidious was related to that. It has nothing to do with seeing the past spirits of the Sith lords. Yoda himself said that the Sith are ''captivated'' by the physical realm, so Yoda already knows that the ''spirits'' of the Sith doesn't even exists, so that debunks your theory. The reason why Yoda give up is because he wasn't powerful enough to defeat Sidious, not because of non-existent spirits of the Sith lords. The sith are captivated by the physical realm, they don't have spirits like Jedi has. They can't take over the Jedi's body, or not even a Sith's body. Sidious didn't even have any access to Plagueis's power despite killing Plagueis personally. So that's metaphorical. Just like Rey saying she is all the Jedi. Nope. Kylo was in the same situation as Vader. Sidious gives him a direct order, which is killing Rey. Kylo had to obey Sidious. Otherwise Sidious was going to turn his fleet against him if Kylo doesn't kill Rey. Spoiler Sidious's influence over Kylo was even bigger than Sidious's influence over Vader's. Sidious was basically inside of Kylo's head from the beginning, Sidious was manipulating him through Vader's and Snoke's voices. And Snoke was Sidious's puppet. So nothing actually is different between Sidious-Vader and Sidious(Snoke)-Kylo. So it's baseless to say that Kylo can defy Sidious's orders. He couldn't. Another obvious thing is that Snoke as well ordered Kylo to kill Rey in the Last Jedi, and Snoke was Sidious's puppet from the beginning. So Sidious really wanted Rey dead. Sith didn't live inside of Rey when she killed Sidious, she was still a Jedi. Sith didn't live inside of Vader when he killed Sidious, he was still a Jedi. So your theory still doesn't make sense and it's baseless to say that the past ''spirits'' of Sith lords can possess a Jedi's body, they never did, and they simply can't. I already proved that Plagueis wasn't even part of Sidious's power according to the novel, when Sidious personally killed Plagueis by himself. So we know that Sidious didn't have any access to the past sith lord's memories and their powers, so that's only metaphorical. Just like Rey saying ''I am all the Jedi''. Another reason why the past Sith lords spirits can't actually live or do anything is because the Sith are ''captivated'' by the physical realm, they can't have spirits like Jedi has. Which is why Plagueis doesn't have any spirit inside of Sidious, and he doesn't talk to him, like the Jedi Force ghosts talks to other Jedi. If you read the discussion as whole, Jedi_Sith_Smuggler_Droid says that the past spirits of the Sith (which is proven that the Sith can't even have spirits like the Jedi but nevermind that) can possess the other Jedi's body against the Jedi's will. Which I find it ridiculous. I think that's just an excuse why Yoda failed beat Sidious, but even as an excuse that doesn't make any sense. So what you're saying really doesn't matter, because if that theory was true, the past spirits of the Sith can take over Anakin Skywalker's body as well, against Anakin's will. But it never happen anything like that. Because Jedi_Sith_Smuggler_Droid claims that if Yoda killed Sidious, the past Sith lords would possess Yoda's body against Yoda's will, so Yoda knew that, and that's why he gave up on fightings. That absolutely makes no sense, for one, Yoda himself said the Sith are captivated by the physical realm, so he didn't know anything like that, and secondly; if Sidious and the spirits of the Sith had any power like that, since Sidious has foreseen Vader's betrayal in RotJ according to TRoS novel, Sidious wouldn't wound Vader or he wouldn't stop Luke when Luke was trying to kill him, he would send Vader away from the throne room, they would be alone in that room and Sidious would just let Luke to kill him, so the past sith lords would take Luke's body. But we know that didn't happen with Vader when Vader killed him and it didn't happen with Rey when Rey killed him, so that's nothing but a baseless excuse on why Yoda didn't beat Sidious for now. I also agree what you say about Windu, Sidious absolutely wasn't faking to lose against him, which is why he send a powerful Force lightning to kill him, which could actually kill Windu if Windu wasn't prepared to deflect it right back at Sidious. And not only Sidious said twice that Kylo should kill Rey in TRoS, Sidious also tried to do the same earlier by using Snoke in the Last Jedi, Kylo was going to kill Rey, or Snoke was going to kill Rey, it would be the same result, and that was Sidious's wish, because Rey wasn't going to turn to the dark side. And like Snoke said she had a true spirit of a Jedi, she needed to die for that reason. Spoiler Sidious wasn't going to make the same mistake he did with Luke and Vader. Snoke also said the same that Vader made the mistake on not killing Luke, so which is why they (Sidious and Snoke) forced Kylo to kill Rey this time.