From the guidelines:
"Do not post about trading the following:
Forum bells or forum shop items in exchange for real money, gift cards, or items representative of real money.
Animal Crossing bells, items, or villagers in exchange for real money, gift cards, or items representative of real money.
Duplicated, hacked, or power-saved items in Animal Crossing.
Any other item in conflict with our rules and guidelines.
Items representative of real money include download codes for games and other digital content and physical items with real money value."