In the clip below, King Dedede, the sour-faced penguinesque character, gets possessed by a gooey black spirit who wants him to fight Kirby.
In the next clip, the evil spirit loses the fight, and Dedede returns to his snooty self. Waddle Dee, the little red guy, invites him on their quest.
In the last clip I selected, everyone happily skips stones while they wait for the portal to the next world to open. Kirby's enthusiasm frightens them.
From my experience, taking the simplest possible approach to necessary, everyday bits of animation -- walks, entrances, exits -- frees an animator to act and brings the animation closer to cartooning at the same time. Cartooning is mostly humor and instinct. You never question the physics of Lucy kicking Charlie Brown in the butt in a Peanuts strip. It just feels right.
Obviously, there are times and even whole films for complexity, but it doesn't suit characters like Kirby and company. Therefore, Kirby 64's story scenes use a lot of cartoony shortcuts. That's not a bad thing, because the economy and appeal of the animation is quite exceptional for a video game.
Notice how the attitude in this scene comes first and the walk is an afterthought. Dedede is focused on the crystal, so a soft landing that doesn't interrupt his waddle or his hungry stare is quite appropriate.
Here's another cartoony animation principle that Kirby 64 honors: "Just get the character out of there!"
And that principle's brother: "Just get the character in there!" The sooner and more abstractly a character enters, the more time you have to establish his attitude, as possessed Dedede demonstrates. (Also note the spooky underlighting that one of the artists applied to Dedede and nothing else in the scene. Nice touch!)
Alas, the flaw I mentioned is a crusher -- the lack of proper squash and stretch in some scenes. When Adeleine, the kid in the beret, anticipates for a take, her model compresses in one direction. I still wanted to post this scene for its entertainment value, and to show the eye-bugging that happens on Dedede and Waddle Dee. The less perfect the model, the more easily you can break it!
All technical (and cheat-related) analysis aside, the acting is terrific, despite the characters' limited expressions. Moments like Dedede pushing back Kirby's face and turning to inspect the crystal more closely establish character types in a heartbeat.
Even the game's best-animated scenes are not the best animation I've seen, but they are all charming and direct, and they feel very spontaneous when you consider the typically painstaking CG process. I always loved HAL Laboratory's games for being some of the most whimsical to grace Nintendo's systems, and now my appreciation goes a bit deeper.