Splatoon is a new franchise developed by Nintendo for the Wii U.
If you talk to the amiibo box near the Battle Dojo in Inkopolis Plaza, you can scan a compatible Splatoon character amiibo to bring them into the game. The amiibo will present you with a list of single-player challenges based around a specific weapon that reward you with increasing amounts of coins. Completing all 4 challenges in a row will reward you with exclusive Gear from a set, an arcade minigame or blueprints for a replica Hero weapon.
Your amiibo must have a nickname in order to be used.
Below is a list of all amiibo compatible with Splatoon.
These amiibo unlock exclusive challenges, gear & weapons: