amiibos can only store data for a single game at a time.
While Nintendo's amiibo figures are set to debut alongside 'Super Smash Bros.' for the Wii U, Nintendo has already outlined two successive waves of figures. The third wave includes non Nintendo characters like Mega Man and Sonic as well as classics like toon Link and Bowser. In a new video, Nintendo goes through the amiibo functionality in several games, including 'Smash,' 'Mario Kart 8' and 'Hyrule Warriors.'
What has also emerged is an interesting limitation, the amiibo figures can only store data for a single game at a time. So in a game like 'Super Smash Bros.' the character data is stored in the amiibo, and the data would have to be erased in order to store another game's data. While this is unfortunate, it doesn't affect games like 'Mario Kart 8' where the figure doesn't store data but rather is just used to unlock content in-game.