Pokémon Mystery Dungeon: Gates to Infinity

The player is a human who has a dream about a Munna being chased by a Hydreigon and calling for help. The human then wakes up in a strange world and discovers they have been turned into Pokémon, and starts plummeting down through the sky to the ground. When they wake up, they find another Pokémon leaning over them and asking if they are okay. After introductions, the player accompanies this Pokémon through a cave to a desolate plot of land, which the Pokémon purchases. The Pokémon tells the player their dream of creating a Pokémon Paradise, and asks the player to help them. The player agrees and they become partners.