Transform lets the Pokémon Pokopia protagonist imitate another form.
The protagonist is a Ditto, and Transform is the signature move associated with Ditto’s ability to copy another Pokémon’s appearance. In Pokopia, that concept is adapted into the story: Ditto takes on a human form and becomes the player character guiding the restoration of the world.
This is more specific than Mimic. Mimic copies a move, while Transform changes the user’s form to resemble another Pokémon. Substitute creates a decoy and Metronome selects a move at random, so neither explains the protagonist’s identity or human appearance.
Pokopia uses the idea creatively rather than presenting Ditto as an ordinary battler. The transformed character can explore, build, gather resources, and help establish a community. The move therefore connects a familiar piece of Pokémon lore to the game’s unusual premise.