I honestly don't see all the calls saying that any of the team solos. Revan for instance was not alone when he faced Vitiate, yet was defeated thoroughly by him. Vitiate feared to have The Dread Masters acting in concert with one another and saw them as doing so as more than a real threat to himself. It takes an entire team of the most noteworthy combatants in the galaxy to take them down each time and then to finally defeat them, and they never face the entirety of the council in peak, corporeal form as would be seen here.
My team was indeed overkill so that point I submit and I'll have to redo the thread, but I don't see any of this crew walking in and 1 v 6ing the entire council. Palpatine feared going near Gethzerion or having her get off world and coming anywhere near him. Considering that he saw her as a valid threat to his life that doesn't suggest to me that he would have what it would take to deal with the raw power and arcane knowledge of the Council on his own. Were his abilities ever so great that he could reach out and drive an entire fleet into madness through the Force? Were his or Plagueis' machinations with the dark side ever enough to corrupt planets or moons the way the Council did with Oricon? Almost the whole of them had means of striking even powerful Force users dead in nearly an instant from their showings.
I'm game for arguments otherwise, so what is it that suggests to those saying so that anyone would be capable of soloing this collective?
Revan was thoroughly defeated by Vitiate in single combat, in the heart of Dromund Kaas's immensely powerful DS nexus. Once he had Scourge and Meetra on his side, Scourge saw various possibilities where either side could win, but he betrayed Surik and struck her down, which allowed Vitiate to cheap-shot Revan. The Emperor never "thoroughly defeated" the entire trio.
Vitiate had the Dread Masters acting in concert for years, lol. And after the DM threat, the Wrath later suggests that they're nothing next to Vitiate.