I am not sure if Sidious (DE) have been considered.
Also, I don't get the preparation argument either. What kind of preparation?
I am not underrating any Sith.
I am focusing on the greater dynamics. Emperor Vitiate can unleash vastly destructive Force powers, he have demonstrated the capability to crash entire Dark Council. Some Force powers/techniques are simply too much to handle. Force Storm (Wormhole) is an example.
Each member of the Jedi Strike Team led by Tol Braga is among the strongest and most resolute Jedi of the Order. It is likely that each have formidable capabilities and talents. Conventionally, a Jedi Strike Team of this caliber should be able to take care of most threats in the galaxy.
Since any version of Sidious isn't specified, it is his peak version which is DE Sidious.
Well, he is a master at sorcery and charging his powers before combat. He gathered the council to eliminate them and pulled off something far above his general feats. It is obvious that he boosted his powers to such an extend. The ritual in Natemha must have had great impact on his capability to multiply his powers through certain preparations.
Again, he won't have the time to charge like that. He will have to use quick attacks and he'll be overwhelmed at some point. Unlike him, the team can separate a bit and the other 3 sith can hold him off while Sidious charges something deadly. So this argument only proves you wrong.
Moral of the story? Scourge was proven wrong, his opinions are not infallible.
When?
I am not denying the possibility of HoT's further power progression by the time he confronted Emperor Vitiate for the second time. HoT would have further grown in power but my contention is that he cannot realistically grow considerably in power in a short span of time.
They say it throughout Chapter 3 and to Satele towards the finale.
Are you assuming that they were learning something else on the Emperor's Space Station? Either way, they had used Dark Side energy, hence the red coloration during the cutscene.
It's been almost a year in game. Similar growth happens in the mythos, even during this small time frame.
Scourge states this after the Hero had beaten him. By that time he would be well aware of the Hero's strength. He would have to be fairly certain he could have defeated her previously. He obviously sensed her power at the time and knew it was not enough.
Before the attack on the Dark Temple. She claims to be stronger than the first time she fought Vitiate.
And that contention is wrong. Bane grew considerably in mere months, so did Jaden Korr, Galen Marek, Revan etc. Nox goes from an untrained slave to beating Jedi Masters in under a year.
While turned to it by Vitiate, yes. Unknown if she retained any grasp of the dark side after shaking off his domination though.
Try weeks or months. The Hero had plenty of time to grow.
T'ra Saa (Grand Master battle meditator)
Cade Skywalker (Skywalkers never hurt)
Celeste Morne (Used to keeping powerful sith out of her head, the Muur talisman can be a nice surprise)
Roan Fel
Very power battlemeditator, probably the strongest one. Skywalker, Morne with her necklace, and another force-powerful strong blade. I think they should at least be able to give a good fight of it.
I think it'll work.
I'd replace Ulic with Thom, just to be absolutely sure of having a force edge, but similar idea.
But, one, that's a single sword wielder, and two, this is with two very powerful people giving force support. Even if it's not a blitz I think they'll win.
Nomi and Arca together should be able to prevent him from using the force to dictate the battle.