Here's why:
* No Online Features: Pokemon Platinum does not have online features like trading or receiving mystery gifts from friends.
* Wireless Communication: The only way to trade or receive gifts in Pokemon Platinum is through wireless communication with another DS system using the DS Download Play feature.
* Mystery Gift Events: Mystery Gifts in Pokemon Platinum were mostly tied to specific events, where you could receive special Pokemon or items through the game's Mystery Gift function. These events were usually time-limited.
So, if you want to trade Pokemon or exchange gifts with a friend, you'll need to do it in person through the in-game wireless communication options.
If you're looking for a game with online features and mystery gifts, you could consider playing a later Pokemon game like Pokemon Black/White or later, which feature online connectivity and more robust ways to receive mystery gifts.