The first details for the functionality of the Metroid: Samus Returns amiibos have been revealed on the game's official Japanese website (courtesy of GoNintendo), and they unlock special abilities, an extra difficulty, art galleries, and a soundtest. Here's the full list:
• Samus Aran (Metroid Series): Elon Reserve Tank (special ability recovery); Metroid II Art Gallery (unlocked after beating game)
• Metroid (Metroid Series): Metroid Marker (tells you location of nearest Metroid); FUSION Difficulty Mode (unlocked after beating game)
• Samus Aran (Super Smash Bros. Series): Missile Reserve Tank (missile recovery); Concept Art Gallery (unlocked after beating game)
• Zero Suit Samus (Super Smash Bros. Series); Energy Reserve Tank (energy recovery) Sound Test (unlocked after beating game)
Metroid: Samus Returns will be released on September 15 on Nintendo 3DS. Will you be using your amiibos?