Which character helps Ditto investigate why humans and Pokémon left in Pokémon Pokopia?

Professor Tangrowth helps Ditto investigate why humans and Pokémon left in Pokémon Pokopia.

Professor Tangrowth is a Tangrowth who has taken on the role of studying the environment. After Ditto arrives in the abandoned world, the two characters work together to understand the damaged landscape and restore habitats for the surviving Pokémon.

The character is not Professor Oak, despite the game’s connection to the Kanto region. Oak is a famous researcher from earlier Pokémon stories, whereas Professor Tangrowth is a distinctive Pokopia character created for this post-apocalyptic setting.

As the story develops, Ditto and Professor Tangrowth discover clues left behind by humanity. These logs eventually explain that environmental phenomena made the world inhospitable and forced humans to leave for outer space.