The Dedede Brooch (デデデの時限スイッチ, Dedede's Timed Switch) is a non-gameplay item originating from the Subspace Emissary in Super Smash Bros. Brawl. It appears to be an adhesive, golden brooch with an image of King Dedede's face embossed on it. The brooches are used to revive the wearer from their trophy state, activating after a certain amount of time has passed.
Before the story of the Subspace Emissary began as presented by Brawl, King Dedede learned about Tabuu's motive and the attack that would turn everyone into trophies (the Off Waves) by witnessing the Subspace Army's attack on the Halberd. Aware that Tabuu was likely to attempt to turn everyone into trophies, leaving no one to revive anyone, he set about creating the Dedede Brooch so that even if all known fighters were knocked out, there was still a way to begin trying to revive them. Noticing that Bowser and Wario were beginning to capture trophy-form characters to isolate them from their allies, Dedede decided to start his own collection, ambushing Luigi and stealing Ness and Peach or Zelda (depending on who was saved from Petey Piranha at the Midair Stadium) from Wario's grasp. He then applied the three brooches he had created so far to them, though he had to use the one he was keeping for himself on the princess, and intended to make another later. Immediately afterwards, however, he was ambushed by Bowser and his Koopa Troop and was buried in the ruins of his castle, with the princess's brooch falling off as she was taken away. Kirby later found the discarded brooch and swallowed it.
After Tabuu successfully used the Off Waves to knock out the entire contigent of Smashers that had advanced through the Entrance to Subspace, the Dedede Brooches activated. Luigi and Ness were revived in the ruined castle and decided to revive the nearby Dedede, who was pleased that the plan worked and the group set out to recover their allies. Kirby was also revived and collected the other half of the knocked-out Smashers.