Gameplay
Items can be unlocked by trading with other players or buying them in a shop. Players must trade to complete their collections, as each cartridge's shop offers a different subset of the items. Players receive a regular allowance of coins, using the DS' date-keeping functionality, and can get more by playing mini-games (such as Guess the Number and Hot Potato), typing certain secret words in chat (each word works once per file) and even for choosing to display the credits screen more than once.
Up to 16 players can play wirelessly using one game cartridge; each must be within about 100 feet (30 m) of one of the others to exchange text and picture messages.
Read more about this topic: Ping Pals