200px-PP Catalog
, or Purchase Points, are a currency in the game. After each battle, regardless whether you lost or not, you gain a certain amount of PP. The amount you gain after each battle can be affected by the Calendar. You can also gain PP by leaving the Duel Colosseum with accumulated medals, by opening certain chests in the Story Mode, by getting free PP from the Mognet when a new day arrives.

PP's only use is to buy stuff from the PP Catalog such as unlocking new Stages, unlocking new Characters, Voice Samples, etc. Though the PP Catalog is arguably the most important thing to prioritize as it affects every gameplay mechanic in the game.