Who is the only resident Ditto meets when Pokémon Pokopia begins?

Tangrowth is the only resident Ditto meets when Pokémon Pokopia begins.

Ditto awakens in the Withered Wasteland, a desolate area where the world has deteriorated and humans have disappeared. Tangrowth lives alone there and explains that the other residents vanished long ago, although Tangrowth does not know exactly where they went.

Tangrowth later becomes known as Professor Tangrowth and acts as an early guide for Ditto. After a Pokédex is found among items in the wasteland, the two begin restoring Pokémon habitats. As the land improves, more Pokémon gradually return and help with different tasks.

Tangrowth is easy to confuse with later characters. Slowpoke is important because its yawns help bring rain, while Snorlax appears in the gloomy Bleak Beach area. Rotom appears later in Rocky Ridges as DJ Rotom. At the opening of the story, however, Tangrowth is the sole resident Ditto encounters.