Much like Skylanders, nintendo is going to be releasing collectible figures that also interact with your games. How it works is you place the figure on your Wii U gamepad, the gamepad reads your data and enters the figure into the game.
It was shown off with Smash Bros. and each figure has a chip that saves your data. The figure saves your playstyle and evolves based on how you use it. The characters you enter in with the figures won’t be playable for Smash Bros. but you can use them to assist you in fights or you can fight against them to train yourself. Nintendo claims that facing against your evolved amiibo will be nothing like facing a standard CPU opponent.
They also confirmed that it would work with other games such as Mario Party 10 and Mario Kart 8 but didn’t go into details on those. They also showed off an attachment that will be releasing later that lets you use amiibo on the 3DS.