Attention the price is sometimes linked to speculation: all figures amiibo cost between 13 and 15, especially not pay double (see triple!) Because of a stock shortage that Nintendo should settle at progressively .
Compatibility level of the figure for the Wii U (I have not tested on 3DS)
Mario Party 10: Unlocks amiibo Party mode lets you add tokens (you earn during the game to store) to this character and customize the trays in amiibo Party
Hyrule Warriors: Get objects as well as bonus weapons (like all amiibo)
Super Smash Bros. : Like all amiibo allows a character who will fight together with you and advance level (until level 50)
Mario Kart 8: unlocks a special costume for your Mii
Important note: a backup amiibo not one game, so you can not (for example) saving chips in Mario Party 10 and safeguard the level of a non-player character in Super Smash Bro. We'll have to make choices so!