Nope, not that simple, I wish it was.
I had to go into Wii U settings, register the Amiibo then go into the Amiibo settings in Smash Bros and register it there as well before I was able to use it.
Skylanders/Disney Infinity figures are much easier to use.
I am not the only to find the set up a pain-
http://www.geek.com/games/nintendos-amiibo-setup-process-is-far-from-effortless-1609295/