What working title came before Pocket Monsters during Pokémon's development?

Capsule Monsters was the working title before Pocket Monsters during Pokémon's development.

Satoshi Tajiri initially imagined a game about collecting creatures and exchanging them between Game Boy players. The project was first called Capsule Monsters, a name inspired by the idea that creatures could be stored in capsules. Game Freak later shortened the concept to Capumon during development.

The name eventually changed because Capsule Monsters could not be trademarked. The project became Pocket Monsters, which was later romanized and abbreviated internationally as Pokémon. This history explains why Pokémon merchandise and game documentation sometimes use the phrase “Pocket Monsters,” especially in Japanese contexts.

The capsule concept was not arbitrary. Tajiri had been influenced by Ultraseven, a Japanese television series in which monsters could be stored in capsules, as well as by his childhood hobby of collecting insects. The final design combined those inspirations with the Game Boy link cable, turning creature collecting into a social activity involving trading and battling.