In Veilstone City by the gym, there is a girl that will kindly give your Pokémon Massages. This is a common thing within Pokémon games and helps raise their Happiness. However, while the person massages your Pokémon, items can be found. These items are for Super Contests. Below is a list of the accessories found;

Item Sprite
Eerie Thing
Glitter Powder
Humming Note
Mystic Fire
Perculiar Spoon
Poison Extract
Pretty Dewdrop
Puffy Smoke
Shimmering Fire
Shiny Powder
Snow Crystal
Wealthy Coin