Let's see what traumatizing things Kirby has gone through:

-fought two beings that bled,

-a possessed King DeeDeeDee five times(Dark Matter Triology, Triple Deluxe((does mind control count?)),Star Allies).

-Nightmare in his true form.

-a being made out of hatred.

-this.

-Magolor after he(Kirby) defeated Landia.

And that's only the game series, as lots more things happened in the anime that traumatized Kirby, like the robot dog and Chilly melting before his eyes.