The player-controlled protagonist in Pokémon Pokopia is a Ditto.
This Ditto uses its transformation ability to imitate a human, creating the game's distinctive player-character premise. Rather than controlling a human Trainer who commands a team, players guide a Pokémon that adopts a human-like form while restoring the surrounding world.
The transformed Ditto can customize its appearance, including skin color, hair color, and clothing. It can also learn moves from Pokémon it befriends, using those abilities to interact with the environment and complete practical tasks.
Ditto should not be confused with Professor Tangrowth, the Pokémon who helps investigate the abandoned world. Tangrowth is an important story character, but the player character remains the transformed Ditto throughout the game.