What was the Japanese name of the original Pokémon games' blue version?

The Japanese name of the original blue version was Pocket Monsters Blue.

Pokémon Blue was first distributed in Japan as a special edition for subscribers to CoroCoro Comic in October 1996. It later received a general retail release, with updated artwork, revised dialogue, and technical changes compared with the first Red and Green versions.

The international Pokémon Red and Blue releases were based largely on the Japanese Blue version. However, the international games retained the distribution of Pokémon associated with the Japanese Red and Green pair, so the two naming systems are not identical in every detail.

The title Pocket Monsters reflects the franchise's original Japanese branding. English-speaking markets adopted Pokémon, an abbreviated form that also avoided conflict with an existing trademark in the United States.