How do you get Ditto ben 10 protector of earth ds?

To unlock Ditto in "Ben 10: Protector of Earth" for the Nintendo DS, you need to progress through the game and defeat the boss in the "Jungle" level. After defeating the boss, Ditto becomes available as a playable character. Make sure to explore the game thoroughly to ensure you meet any additional requirements for unlocking him. Once unlocked, you can switch to Ditto in the character selection menu.