I'll give you some info on the less known acolytes of the EU team:
Tol Skorr: was defeated by EU Vos towards the end of the clone wars, but he was still capable of holding his own for some time. Against Vos, he didn't perform much worse than Aayla or K'kruhk. He also survived a fight against a Krayt Dragon
Kadrain Sey: Skorr's partner, she lost to 22 BBY Vos despite having SKorr's help.
Saato: she was stronger than 22BBY Aura SIng, and was also capable of strangling 22BBY Anakin. In the end she was slain by Skywalker in 22 after giving him a very good fight
Sev'rance Tann: a Chiss dark jedi and one of Dooku's earliest recruits. She was stronger than the Jedi Echuu Shen Jon, who beat her only by using the dark Side. She was replaced by Bulq
Rhad Tarn: A Jedi knight who was able to hold his own briefly against 22BBY Ventress. He also almost overpowered fellow Jedi Knight Sian Jeisel, but was ultimately slain by her
I was giving Krell the better position mainly because he’s a Jedi Master, has twin double bladed sabers, physical advantage and so on. I just find him much higher compared to Barriss even if he doesn’t have much.
In all honesty despite not having much, he's probably the most dangerous here just due to the fact he has a unique way of fighting IE: Two double bladed sabers.
With Ventress and Vos, one could reasonably figure out how to fight them. But with Krell it would be a little bit different. Not impossible mind you, he has flaws in that from what I recall, he's very arrogant and overconfident in his personality/abilities which could end up with his downfall.
Yeah, with his fighting style I could see him taking on the weakest three of the other group: Sey, Tann and Skorr. Even all three at the same time possibly. Against Saato and and Tann the result is is less certain. Saato was pretty close to post-AotC Anakin in power. Would you favor Krell over that version of Anakin? I could see saato winning with a lot of difficulty. Between Tann and Krell I'd give it to the latter, Echuu was a solid jedi, but still...
I mean power wise Canon vs Legends, there does seem to be a rather large gap. What Krell showed isn't exactly anything out of realm for your standard Jedi Knight/Master to pull off. His most dangerous aspect seems to be his melee combat ability which he seems to favor, naturally so, so that's what's gonna make him dangerous here not so much his Force prowess.
Given how high thinking Tann was in the tactics department, she can probably come up with a way to take out Krell.
Btw I don't think you specified a location, so that would help.
Well then that doesn't leave many options. Really though, it's probably gonna be best to have the 4 best fighters on Krell while the other 4 deal with Ventress/Vos. Again, I feel Barriss is out of her depth here and she can just get dismissed.
In which case, I can't really see anyone taking on 4 Dark Jedi, even Krell with his rather different fighting style. If anything, the 4 against him could just combine their power if need be and finish him off that way. When he's down, they just go and reinforce the other 4 against Ventress/Vos.
Everyone in that show gave a ‘fight’ to Skywalker, plus he was clearly holding back and when got serious he floored her. Plus why is that an impossibility for anyone here to do the same, when that is pretty much all she has to her name.
Yeah it's decent for her, but I'm not seeing why anyone else here can't do the same.
But none of them are really featless. I mean maybe in personal feats, but they still do logically scale from those who have shown much better than Barriss. Apart from her fight with Anakin, I really don't recall her doing much.