Japan certainly loves their Monster Hunters and Pocket Monsters. Nintendo completely dominates the top 10 except for the coveted number 1 position which was taken by Monster Hunter Portable 2nd G. The game that helped the PSP outsell the DS by wide margins for months in Japan.

Bold=Total sales in 2008

1. PSP-Monster Hunter Portable 2nd G 2,507,400
2. DS-Pokemon Platinum 2,125,348
3. Wii Fit 2,024,113
4. Wii-Mario Kart Wii 1,973,089
5. Wii-Super Smash Bros Brawl  1,808,709
6. DS-Rhythm Tengoku Gold 1,320,047
7. DS-Dragon Quest V 1,228,014
8. DS-Kirby Super Star Ultra 724,608
9. Wii-Animal Crossing City Folk 709,640
10. Wii Sports  694,765

Note: Wii Sports is not bundled with the Wii in Japan

Source