These badges first appeared at Castle Dedede, when King Dedede was putting them on the trophies of Luigi, Ness, and Peach/Zelda. He only had three at the time so he was reluctant to give the princess his personal brooch. He did this and decided to make another later. Suddenly his castle caved in and Bowser'sKoopa Troop raided the place. Bowser stole the princess trophy and ran off, escaping in his Koopa Clown Car. before he left he threw off Peach/Zelda's brooch and Kirby found it and ate it.
Later in the story when Tabuu'sOff Waves turned all the fighters into trophies the brooches revived Kirby, Luigi and Ness.
The Dedede Brooches have one use. It is to revive those who have it on their person when there is no one left to revive anyone.