What handheld platform was the first Mega Man Battle Network made for?

The first Mega Man Battle Network was made for the Game Boy Advance.

Capcom released Mega Man Battle Network in Japan on March 21, 2001, as a Game Boy Advance launch title. It is the first game in the Battle Network sub-series, which reimagines Mega Man in a world dominated by internet technology rather than traditional robotics.

The game follows Lan Hikari and his NetNavi, MegaMan.EXE. Players alternate between Lan's real-world activities and MegaMan.EXE's battles inside cyberspace. Its real-time tactical combat uses Battle Chips, a system influenced partly by the popularity of collectible card games.

The Nintendo DS can cause confusion because an enhanced version, Mega Man Battle Network: Operate Shooting Star, was later released for that system in Japan. The original game, however, debuted on the GBA; later Virtual Console and Legacy Collection releases do not change its original platform.