Can You Trade Pokémon with Two Games but One Cartridge? No—Need Two Systems/Copies

No. Trading requires two game cartridges (on separate systems or two copies on one system) and a connection (local wireless or internet).

Why

• Games only trade within same generation (e.g., Diamond↔Pearl, not Diamond↔Black without special tools).
• Communication needs two active game instances.

How to Trade

• Local wireless: Nearby DS/3DS/Switch.
• Nintendo Network: Online via internet (needs account).
• Pokémon Bank: Cloud storage/transfer for Gen V+.

One cartridge cannot trade with itself.