Which Nintendo handheld was Pokémon Diamond and Pearl released for?

Pokémon Diamond and Pearl were released for the Nintendo DS.

The games were designed as fourth-generation Pokémon role-playing titles for Nintendo's dual-screen handheld. Their hardware shaped several features, including the Pokétch, a touchscreen-based device displayed on the lower screen, and wireless communication for trading and battling.

Diamond and Pearl launched in Japan on September 28, 2006, before reaching North America in April 2007 and Europe in July 2007. They also connected with earlier Game Boy Advance Pokémon games, including Ruby, Sapphire, Emerald, FireRed, and LeafGreen, through the Nintendo DS's Game Boy Advance cartridge slot.

The Nintendo DS is easy to confuse with the later Nintendo 3DS, which hosted the remakes Pokémon Omega Ruby and Alpha Sapphire. Diamond and Pearl themselves were not Nintendo 3DS releases; their enhanced companion title, Pokémon Platinum, also appeared on the original Nintendo DS.