Right now K. Rool is new, so his easy-to-learn punish playstyle is difficult to play against. But as someone who's played way too much King K. Rool in Quickplay, his weaknesses are very noticeable. (Any fast fighters like Inkling, Falcon, or a Fire Emblem swordsman usually shield with perfect timing and zone in.)
- His projectiles are slow and predictable. Every counter to Samus applies to K. Rool, but is much easier to dodge.
- Also, you can steal his crown. Either keep it on the ground away from K. Rool, or pocket it forever with Villager/Isabelle.
- His recovery is the same as Duck Hunt; slow, predictable, and can't be cancelled. Just with a small propeller attack on top. All Duck Hunt counters apply, except the fan makes Dairs a little harder.
- His air game is lacking. Large fighters are easy to hit, and if you jump towards him, you can most likely hit him before he hits you.
- It's easy to escape the ground stun combos before high percentage. You just have to mash buttons to jump out, then avoid grabs as if you were fighting a grab-hungry Ness or Mewtwo.
- The hardest combo to counter is his Blunderbuss edge-guarding. Any projectile or long-range attack will knock him out of it, and some stages will let you hit him underneath the platform. Sadly, some fighters like Little Mac will always have a hard time against that tactic.
TLDR; jump over projectiles, use aerial attacks, hit him in the air, spam escape ground stuns, and don't be Little Mac