Even with the knight fight in mind I think they were still holding back against them. I think that in Snowgrave, vs Spamton, Kris wasn't holding back AT ALL.
Snowgrave Kris almost certainly fucking hated Spamton for facilitating fucking his friend up, and as a result showcased far better healing than Ralsei, and far better damage output than Susie in the solo fight.
Kris seems to prefer not to take center stage it seems, but the Snowgrave NEO fight proves to me at least that they're a great deal stronger than the rest of the party.
Which sorta leads on to the sort of super schizo theory I'm developing that this isn't the first time that the prophecy has played out at all, and that Kris may well have been through it all before, possibly with Dess and Asriel.
We know at least that Ralsei's prophecy is a lie. "A human, a monster, and a prince from the dark" where in reality it's "The Cage, with Human Soul and Parts" (can only be Kris), "Second, the girl with hope crossed on her heart" (Susie, possibly Dess (Dess wields a sword if she's the knight, Susie has an axe, if it was Susie, why would the prophecy be wrong about her weapon?) .
Love finds its way to the Girl (Possibly Dess again, but LOVE making her the Knight?)
"And third, the Prince, alone in deepest dark" (Built up to make you think it is Ralsei, also can also apply to Asriel as well, as at the end of Undertale, Asriel is left all alone in the underground.
And then last was the girl (Noelle)?
We saw the modified deltarune that had 4 triangles, after all.
Mostly just schizoposting here, but Kris making the Dark Fountains means that he's got a lot of experience with the Dark World prior to any interaction with Ralsei.
I'm almost starting to believe that Asriel didn't go to college after all, but is somehow trapped in a Dark World, and people are just lying to Kris to try to make him feel better.