So I'm not the only person who isn't too impressed with Kratos in Shovel Knight, good to know. Who would you use as a guest character yourself? (Clearly Shimakaze, after all, KanColle is now labeled as the "Savior of Vita" in Japan so Sony owes it to her. No, I'm not joking about the savior part)

It's a tough question actually. Battletoads makes a lot of sense because the franchise was around from the era Shovel Knight wants to revisit and it's a Microsoft property nowadays, but Sony's side would be a dilemma all the same because they didn't really had such a property until the PS1 days. Crash Bandicoot would have made a more or less fitting SK guest candidate back in the '90s, but right now, I honestly don't know what could make a passing guest. I suppose either Ratchet & Clank or Sly Cooper would work, but only because they're "cartoony" enough to be in a game like SK, and even then that's not an option I myself would want, but rather an option that I can see work better than Kratos, or Nathan Drake.
Then again, even Shimakaze would work better than them, at least she has the more fitting potential to make for a boss for a game like SK.