The one thing that sticks out to me is the cheeks that Spongebob usually has in the newer episodes of the show (not sure if they dropped that in the latest ones). Something about them just gets at me.
More importantly, the ways shows like the later seasons of Johnny Test or Wayside or even the newest Fairly Odd Parents season flow animationwise. Other Flash shows like TTG bother me as well, but not to that extent where's it's strangely stilted yet smooth.>>91834282
Kirby's another good example of that, especially in the more recent games where they give backstory to the villains.