It makes sense that they’d all be on there
It makes perfect sense that Nintendo would have every amiibo file already on theSuper Smash Bros. Wii U disc, but this video apparently confirms that fact. Taken by YouTube user Mema Haxx, it shows the character (known as “Duck Hunt Duo” in Europe) in the amiibo section of the main menu. The amiibo hasn’t even been announced yet.
Will the figure come in the inevitable Wave 4? Time will tell, but the possibility that all of the amiibo data is already in the game waiting to be manipulated is interesting.