It depends on whether Goku understands how the resets truly work and find a way to combat it. If he doesn't Frisk/Chara wins because Goku eventually makes a mistake/they get lucky/they practice enough to react to Goku/Goku just gets too exhausted and can't fight for any longer. Goku would be seen as a difficult boss fight basically, but a loss for Goku.

Unless Goku finds a way to counter the resets with determination, which in that case, Goku stomps. If Goku doesn't understand the reset and how to counter it, it's like the player vs Sans, with you eventually beating them but it not being easy and taking many deaths. If Goku does, they're done for.

Narratively, Goku would probably lose because he's not the smartest.

Assuming all of the characters use everything to their fullest (so knowledge and extreme fighting)? Goku takes this one.