It's not just Gundam, it's Gundam on Wii (see: Japan's Crack Cocaine, or DS could fit this).
The problem is it is competing With so many other games. I think the numbers may be a little lower across the board.
Mario Party 8: 180k
Gundam: 80k
Hot Shots Golf 5: 140k
Elder Scrolls: 40k
Guilty Gear: 15k
Dewey's Adv: 20k
With DQ:S around 75k for week 3.
I would cite regulation, but I know you will simply ignore it.