During the game's development, what was the first ever created Pokémon?

During the game's development, the first-ever created Pokémon was Rhyhorn. Among the initial 151 Pokémon, Rhyhorn was one of the earliest designs and served as one of the foundational creatures in the Pokémon franchise. Its creation and inclusion in the game showcased the developers' intention to design a varied and diverse world of Pokémon with a range of abilities and characteristics. Rhyhorn's distinctive design and its evolution line, which eventually leads to the powerful and iconic Rhydon, highlighted the developers' creativity in crafting memorable and unique creatures for players to encounter and collect in the game.