Does the Nintendo DSi Support Multi-Card Play (Multiple Cartridges at Once)?

No. The Nintendo DSi has only one Game Card slot. It cannot read two or more cartridges simultaneously. "Multi-Card Play" (local wireless multiplayer where each player inserts their own copy of the game) requires each player to have their own DSi/DS/3DS system with the game inserted.

Clarifying Terms

• Single-Card Download Play: One cartridge hosts; other DS systems download a temporary client via local wireless. Supported by many titles (Mario Kart DS, New Super Mario Bros., Pokémon).
• Multi-Card Play: Each system has the cartridge; lower latency, full features. Requires one system per player.
• DSi Game Card Slot: Accepts DS/DSi/3DS game cards only. No GBA slot (removed vs. DS Lite/Phat).

If you want multiple players, each needs a DSi/3DS and their own game card (or the host uses Single-Card Download Play if the title supports it).