To be fair, the numbers you would get if you include all games aren't all that different.
Wii would get Wii Fit and Mario Kart Wii up there, rather than 2 random games.
MKWii should sell 3-4 million, and Wii Fit a bit less than that.
X360 would possibly get ODST at 1.5-2 million up there
Nothing would be added to the Ps3.
So in a sense, asking the question this way is more precise, as it lets the repliers focus on the actuality, rather than check old titles.
Edit: Oh, and Wii might get Wii Sports Resort up there with around 5 million as well.
Essentially, X360 and Ps3 will be identical, and Wii will be
Wii Fit +
NSMB Wii
Wii Sports Resort
Mario Kart Wii
Mario & Sonic at the Olympics
Rather than
Wii Fit +
NSMB Wii
Mario & Sonic
Two minor games.
So I like the OPs way of doing it for 2 reasons
1. It will allow the X360 and Ps3 predictions to be more precise
2. It makes a fair competition, rather than make one the Wii will definitely win.