Sidious found a way through one of the doors to the world between worlds in Rebels, these doorways connect different points in time. The clones weren't Force sensitive, his ether contained the life force of everyone touched by the dark side, that blue ether he used to create an artificial battle between anakin, yoda and him and dooku was a conjuration technique it was stronger than Sidious by himself, stronger even than Luke in TLJ.
Also the only way Rey could match Kylo Ren so quickly, or Palpatine could match Yoda in ROTs, is if Plagueis created Palpatine the same way Palpatine created Anakin, which also explains how you can put an ultra powerful Force user into the Galactic Senate.
"She resisted you?"
"If what you told me is true, bring.her.to.me!" -Palpatine puppeteering Snoke
Edited by OverUnityDeviceUAP, 26 December 2019 - 07:16 PM.