From Bulbapedia, the community-driven Pokémon encyclopedia.
Poké Coupons (Japanese: ポケクーポン Pokécoupons) are a form of currency used in Orre and Pokétopia. In Orre, they are merely supplemental to the normal currency of Pokémon Dollars; however, in Pokétopia, they are the only way to get new clothing and Mystery Gift items.
In Orre, they are used only at Mt. Battle, where several Berries are only available, as well as a number of held items. After defeating an entire area of Mt. Battle, a number of them will be won, with the number increasing as Trainers make their way up the mountain. In addition to this, Poké Coupons can also be gained at Realgam Tower through Battle CDs and Battle Bingo.
In Pokétopia, they are won every time a Colosseum is cleared. The amount of Poké Coupons one can win is proportional to the current difficulty rank of the Colosseum, which increases every time the player wins. Most clothing does not require much of them to purchase, however, all of the Mystery Gift items require a large amount of Poké Coupons to be saved up.