Watch Dogs will outsell it significantly. How could it not, it's on more platforms. But on the WiiU, MK should outsell it quite dramatically.
I don't think Mario Kart will do that well though compared to it's predecessor. I haven't seen a compelling reason to buy it over the Wii version (which had the 'cool' little wheel.) And the WiiU doesn't have the same fire for sales the Wii did. I don't think Mario Kart will significantly push WiiU sales either. Sorry, I wish I was more optimistic, but I think the WiiU needs a game that only works on the WiiU that has the general public interest - as did Wii Sports when the original Wii launched (and movement in general.)
I really thought Pikmen would be more of a system seller. It needs... something.