Which main-series Pokémon games first added online trading and battling?

Pokémon Diamond and Pearl were the first main-series Pokémon games to add online trading and battling.

Released for the Nintendo DS in Japan in 2006 and internationally in 2007, the games used the Nintendo Wi-Fi Connection to let players communicate over the internet. The Global Trade Station enabled players to request and exchange Pokémon with people in other locations.

The games also introduced online battles, allowing compatible players to compete remotely rather than relying only on a local Game Link Cable or nearby wireless connection. This expanded Pokémon’s multiplayer identity beyond direct, in-person exchanges.

Diamond and Pearl are fourth-generation games set in the Sinnoh region. They also introduced 107 new Pokémon and added features that used the Nintendo DS’s two screens. Later games replaced the original Nintendo Wi-Fi Connection services with newer online systems, but Diamond and Pearl established online interaction as a major part of the main series.