While Nintendo no longer sells Four Swords Anniversary Edition, and you cannot buy it via the eShop, the copyright is still active. Nintendo’s official stance (as stated in their legal FAQ) is that downloading ROMs of any game, even delisted or "abandoned" titles, is copyright infringement.
The only legal way to own the ROM is to dump it yourself using custom firmware (CFW) on a DSi or 3DS that already had the game installed prior to the eShop closure. zelda four swords ds rom free
Searching for a "zelda four swords ds rom free" exposes you to specific risks: While Nintendo no longer sells Four Swords Anniversary
To understand the ROM hunt, you have to understand the release window. In September 2011, Nintendo was celebrating the 25th anniversary of The Legend of Zelda. To commemorate, they released Four Swords Anniversary Edition—for free. Searching for a "zelda four swords ds rom
For a limited time (roughly four months), anyone with a Nintendo DSi or 3DS could download the game at zero cost. It featured updated visuals, a new "Realm of Memories" level based on The Legend of Zelda, A Link to the Past, and Link’s Awakening, and most importantly: Single-player mode.
Unlike the original GBA version, which required four Game Boys and four link cables, the Anniversary Edition allowed a single player to swap between two Links on the fly.