Amiibo

amiibo (アミーボ) are a line of interactive figurines available for usage with the Wii U and Nintendo 3DS systems.

Function
amiibo are a line of collectable figures or cards featuring numerous Nintendo characters from various franchises. The series debut on November 21st, 2014 with the Super Smash Bros. for Nintendo 3DS and Wii U line of amiibo. Using near field communication via the Wii U gamepad, Nintendo 3DS amiibo adapter platform, or the New Nintendo 3DS touch screen, scanning an amiibo unlocks special content in numerous Nintendo video games.

Currently, there are five Fire Emblem amiibo figures as a part of the Super Smash Bros. for Nintendo 3DS and Wii U line of amiibos: Marth, Ike, Robin, Lucina, and Roy. A Corrin amiibo has been confirmed for future release. On January 18th, 2017, the first Fire Emblem franchise specific amiibo were announced with an Alm and Celica amiibo slated to be released on May 19th, 2017.

Fire Emblem Fates
Upon scanning a Marth, Ike, Robin, or Lucina amiibo, the scanned character will appear as a NPC wandering the player's My Castle in the south. Like other My Castle features, the visiting amiibo character will activate a short event then disappear. Players will need to complete a map in order to resummon the amiibo character again. All other amiibo aside from the four mentioned have no compatibility with Fates.

The first two scans with an applicable amiibo will gift the player an Accessory only available to that character. The Accessory is tied to the answer the player gives to the character:
 * Marth gives the Dragon Headpiece (Tiki's circlet) and Marth's Tiara.
 * Ike gives Ike's Pauldron and Yune's Pauldron (Lehran's Medallion).
 * Robin gives Robin's Books and a Dragon Feather (Grima's wing feathers).
 * Lucina gives a Bear Hat and her Butterfly Mask.

After two conversation scans, the third time the amiibo is scanned, the character will request a battle between the player's army and their small squad at the Plains of Hoshido. After defeating the amiibo character's forces, they will join the player's army for free. Subsequent scans will make them appear in one of the shops. If they appear in any of the Armories, they will sell weakened versions of their signature weapons. If they appear in the Accessory Shop, they will sell their unique Accessories.

Fire Emblem Echoes: Shadows of Valentia
Scanning an Alm or Celica amiibo unlocks a special dungeon in Echoes. Additionally, scanning their respective amiibo also allows the player to create a phantom version of their unit, saving the data of the current Alm and Celica in the game into the amiibo. These saved versions can be used in battles using the Summon amiibo command.

The Fire Emblem amiibos from Super Smash Bros. for Nintendo 3DS and Wii U are also compatible with Echoes and will summon phantom versions of those units.

Other Compatible Games
The five released amiibo can be used for the following games with the following effects in game:
 * Chibi-Robo! Zip Lash - Unlocks in-game figurines of Chibi-Robo imitating the scanned amiibo's pose. This feature is not compatible with Roy, Corrin, Alm, or Celica. Subsequent scans with Marth, Ike, Robin, and Lucina and all scans with Roy, Corrin, Alm, and Celica gives the player 50 or 100 Moolah once a day per character, per scan.
 * amiibo tap: Nintendo’s Greatest Bits - Unlocks demos of various classic games.
 * Captain Toad: Treasure Tracker – Gives the player 1-Up Mushrooms
 * Code Name: S.T.E.A.M. - Makes the scanned character usable once per level, although they cannot be revived at checkpoints. (Marth, Ike, Robin, and Lucina only.)
 * Hyrule Warriors - Gives the player a weapon with up to three stars, a random material, or a random number of rupees. Up to five can be scanned daily.
 * Kirby Planet Robobot - Scanning a Marth, Ike, Lucina, or Roy amiibo grants Kirby his Sword ability. Scanning a Robin amiibo grants Kirby his Spark ability.
 * Mario & Sonic at the Rio 2016 Olympic Games (Wii U) - Gives the player Coins or Rings that can be used at the item stand.
 * Mario Party 10 - Allows the player to play Scratch Bonus and win Mario Party points.
 * Metroid Prime: Federation Force - Unlocks a skull-themed recolor for the player's mech.
 *  Mini Mario & Friends: amiibo Challenge - Creates a Mini Spec to navigate a level.
 * Style Savvy: Fashion Forward - Unlocks a special skirt design based on Lucina's outfit. (Lucina Only)
 * One Piece: Super Grand Battle! X – Unlocks a Marth costume for Brook. (Marth Only)
 * Pokkén Tournament - Gives gold or unlocks a special Trainer Customization or Title. Up to five can be scanned daily.
 * Super Mario Maker - Unlocks the ability to use the scanned character as a Mystery Mushroom costume for Mario. (Marth, Ike, Robin, and Lucina only.)
 * Super Smash Bros. for Nintendo 3DS and Wii U - Allows the player to train a computer controlled allied character of the scanned amiibo. (Roy and Corrin can be scanned even without the buying the DLC). Alm and Celica are not compatible.
 * Yoshi’s Woolly World  – Unlocks a yarn print based on the scanned character. The Roy amiibo unlocks a generic amiibo design.
 * Poochy & Yoshi's Woolly World - Unlocks a yarn print based on the scanned character.

Trivia

 * The first physical non-E-Book item ever sold through Amazon.com Mexico was an Ike amiibo.