I'm not sure.
Katarn isn't on any of their levels at all, and unless you subscribe to the notion that he's a good running interference I think it can go either way. Caedus mentions how he could've easily demolished the team (with Kyle) regardless, and he dismissed him without much ado even when he had help. I strongly doubt he'd make much of a difference, and as skilled as Jaina is she isn't on her brother's level.
He's not on their levels, but he's good enough that he's not easily dispatched either, even solo he can hold defense for a little. Jaina's swordwork was pretty close to Caedus's, an extra blade there is a major, major tipping point. Whenever Caedus seems like he might have an edge, Kyle can move in to take the load off and give Jaina room to regroup. When Caedus is on the back heal, Kyle can add a little gas.
He's only a secondary role, but heck, take a look at how much Savage was able to help Maul in sabers against Sidious, even though solo he dies in about four seconds.
Remember, Katarn was one of the few Jedi Caedus took as a potential danger, and this is exactly why.
And while Luke helped Jaina a little, it really wasn't much, just illusions and such. Less help than the fully-committed Katarn provides.
Yeah, Jaina is pretty close to Caedus, agreed. And I mean, it's not like during their fights there were any circumstances that could have even slightly benefited her, either, or yeno, even a multitude of quotes including on her own end stating that Caedus is far more powerful than her and that she'd need every advantage possible in order to defeat him.
Totaaaaaaally not far at all. 👆
If this was Plagueis, people would be saying he wins. I thought most people considered the two comparable? Caedus seems to be the only big bad sith lord that people say loses against duos like this, very strange line of thinking.
In fact, I'd bet on a lot of people thinking Dooku could take this duo. The views on here are so wishy washy, one day it's this, one day it's that.
Caedus wins.
It's a close fight, but Caedus wins. He's just better than either of them individually in all areas, and he's significantly above Kyle in some of them. As a whole, both of them are practically outclassed - Jaina can still hold her own for a time, but Kyle would get brutalized on his own. Kyle can provide some decent support for Jaina which keeps the duo from being absolutely outclassed, but they lose in a great fight nonetheless.