Pokethulhu (available free) did a few things of interest to this question:
1 - It approached play as an episode of a fictional TV show.
2 - It put the bestiary in a cartoonily-appropriate world. Just as the pocket monsters were little cute cthuloid monsters, so too was the world a kind of combination of Halloweentown and Lovecraft country.
3 - It used 12 sided dice because those looked like the in-world version of Pokeballs