In Pokemon Platinum, there's no specific item or action that gives you a Member Card. Instead, you'll encounter other mechanics and features that fulfill similar functions, such as:
* The Poketch: This wrist-mounted device allows you to access various applications, including a map, a clock, and a Pokédex. You can also use it to train your Pokémon and play minigames.
* The Global Terminal: This feature allows you to connect with other players online and trade Pokémon, battle, and share data.
* The Pokéwalker: This optional peripheral device allows you to walk your Pokémon in the real world and earn experience points and items.
If you're looking for a specific functionality that the Member Card provided in Diamond and Pearl, you may need to find another way to achieve it within Pokemon Platinum.
Let me know if you have any more questions about Pokemon Platinum!