Fun fact: there are two words in Japanese for caterpillar: いもむし and けむし. One roughly translates to green, hairless caterpillar while the other translates to fuzzy caterpillar. Caterpie and Weedle were designed as complements to each other, one the smooth kind and the other, the hairy one. They use these words as their categories in Japanese too. In English, we only have one word — caterpillar — and it’s a long word. So long, in fact, that there weren’t enough spaces for it in the text box in Red/Blue (character limit was 10), so Caterpie became the Worm Pokémon and Weedle the Hairy Bug Pokémon. Hardly accurate, but they had no choice. Most of the weird, badly translated Pokémon categories are because of character limits, actually.
