You will need an amiibo figure, a compatible game, and a compatible system (Nintendo Switch, Wii U, New Nintendo 3DS, New Nintendo 3DS XL, or New Nintendo 2DS XL). Other Nintendo 3DS family systems are also compatible with amiibo and require the Nintendo 3DS NFC Reader/Writer. 

Do all amiibo figures work with all compatible games?

Each amiibo may work with different compatible games in distinct ways. While a Mario amiibo figure will allow players to battle alongside it in the Super Smash Bros. for Wii U game, the same Mario amiibo will grant them a special Mario racing suit for their Mii characters in Mario Kart 8. Some games, like Super Smash Bros. for Wii U, will save data to the amiibo, while other games, like Mario Kart 8 and Hyrule Warriors, will give you bonus content just for tapping an amiibo to the GamePad.