DoE Bane, Nyriss and Scourge run a gauntlet
Setting: Naboo plains
No amp/prep time.
They get full power and health restored afte reach battle.
1. Grievous, Jango, Pre Vizla and the Death Watch
2. Ventress, Savage, Wyyrlok and Fisto
3. Karness Muur, Naga Sadow and SF Malak*
4. Marka Ragnos, Kyp Durron and Windu
5. Talzin**, Dooku and Maul
6. Vitiate*** and Tenebrous
* Malak gets his SF feats
** Talzin gets her Dathomir feats
*** This is Vitiate at his physical peak
Nyriss has serious speed, skill and lightning feats, she should prove a strong challenge for anyone here.
TOR Scourge is an incredibly well skilled and experienced Sith Warrior whom can self-amp off rage, he's below Revan just like Malak whom isn't some monster powerhouse like Ant makes out.
DOE Bane should prove a fearsome match for any here also.
Scourge has killed a thousand Sith, killed DC members, was a capable match for the HoT and was the strongest warrior in the Sith Empire for three centuries. He was stated to be much more able than his Revan incarnation and more powerful, there is no reason he isn't a match.
Nyriss has husked armoured guards, fought with skill and speed enough to match Scourge and Meetra and was a velnerable DC member and master sorceress, she was even strong enough that the Sith Emperor favoured her to the point of keeping her safe from assassination.
I'm well aware of their feats, lol. As a Jedi, Alek swiftly stomped an "exceptional combatant", and this iteration of Alek proceeded to be stomped by Mandalore the Ultimate in a single strike. Revan defeated Mandalore, and Darth Malak, having improved drastically, was able to challenge Darth Revan (who presumably improved over his former self) in lightsaber combat, a feat at least matching everything you mentioned for Scourge.
Sadow's technique was legendary enough to be the basis for the fighting styles of all Sith Marauders in Vitiate's Empire for millennia. That, and Chris Avellone has confirmed the Kreia quote is accurate, meaning Sadow is far above Kreia and the pre-prime iteration of the Exile as a swordsman. That's definitely above Scourge, lol.
Also, Scourge's Force feats unfortunately don't have a chance at matching Malak's and especially Sadow's.
For Nyriss - Muur dueled at least evenly with Vong Krayt (who approaches Maul as a duelist) despite being seven millennia out of practice, using a lightsaber that he was utterly unfamiliar with, and simultaneously controlling his rakghouls and contesting with Celeste Morne for control over her body. That's above Nyriss's nexus feat of overwhelming the amped novel Scourge and depowered novel Surik, which also involved her gaining the early edge with Lightning.
Nyriss has better power feats to be mentioning, too. The Emperor's decision to protect her was probably because she was a senior member of the Dark Council, lol. Muur is canonically more powerful than either Krayt or Cade Skywalker (and more powerful than that of any other Sith in the galaxy) as of Had Abbadon, and when Dark Times Vader sensed the talisman, he immediately considered Muur being above him in power and comparable to that of Palpatine's, such that their combined power would overthrow Palpatine, but Vader would merely be "trading one master for another". It may not necessarily be accurate, but it was a first impression from Vader, who is hardly known for his humbleness, and it was an impression he gained merely from sensing the Muur Talisman's power.
For feats, Muur absorbed Krayt's two-handed Lightning with one hand whilst simultaneously Draining Krayt, all done with no strain despite mentally contesting with Celeste Morne for control over her body. He later proceeded to unleash a Maelstrom that badly injured Krayt, would've killed Azelyn Rae, and blew away all the other combatants in the vicinity (Shado Vao, Darth Maladi, Cade Skywalker, etc). That's a power feat in exceess of anything Nyriss has ever shown, especially because she's only shown power feats on Dromund Kaas, a considerable dark side nexus.