Clockwork Soldiers

The Clockwork Soldiers, the Toy Platoon (Japanese: パペット・アーミー Puppet Army) are a green, blue, and pink trio of Portrait Ghosts from Luigi's Mansion.

The Clockwork Soldiers are found in the Clockwork Room on the third floor of the mansion. The green-capped plumber found the Soldiers immobile. If Luigi starts the three clocks in the room, they awaken and begin attacking with toy cork guns. As they moved around, Luigi captured each in a hard struggle by sucking their wind-up keys with his Poltergust. After a messy affair, the playhouse's doors opened, granting access to the Roof.

Trivia

 * Only the Blue Soldier gives up the pearls, so it's best to save him for last.
 * In the credits, it should be noted that one of the ending pictures shows Luigi sucking up the blue Clockwork Soldier last hinting that doing so in the game itself could be useful.