Does anyone still mix clashing styles/physics this way in modern animation? My superficial impression is that if a modern character has a gag where, say, its foot elongates to kick an opponent, it has to be part of a foot-elongating species of animal inside, complete with a 10-page backstory, who lives in a fully worked out Elongation Universe that has its own gaming physics engine and subreddit.
The Spiderverse movies have characters with clashing styles and frame rates sharing the screen, but perhaps it fails your second test because they come from different in-story universes. The design, art direction and animation are great, both movies are a visual feast