Sonic Generations sold really great, in fact it is still in the 3DS chart.
Aaaaand if you look at the Guardian top 20, here's the situation in UK for this week.
PS3 (43)
Xbox 360 (29)
3DS (28)
PC (0)
However, NSMB2 had a good debut, and KH3D performed well last month across all Europe. Probably it's out of top 40 due to shortages: for all the week it was sold by external retailers, with just 10 copies available, at 34 Pounds on Amazon, and it's sold out on Game too. Amazon will start selling KH3D again from Thursday. Possibly, we'll see it again pretty highly on German chart this Wednesday.