Titan Dweevil series
The Four Legendary Treasures can be found on that Titan Dweevil. If the Titan Dweevil has all 4 Legendary Treasures it can be Invincible. The only way to make him vincible again, you must remove 4 Legendary Treasures then kill him with your Pikmin. Repeat this until he is defeated, and Louie is saved for last.