Minor Update: I found some information stating that Donkey Kong Land, known in Japan as "Super Donkey Kong," sold about 1.07 million copies for the Game Boy in Japan. So if you were one of those people lamenting that Donkey Kong only represented a small majority of million-sellers on this list, I have got some good news for you.
The Game Data Library, possibly the best source of Japanese game sales figures in the non-Japanese parts of the internet, is currently undergoing an overhaul. I should be able to give this thread a proper update once that is done.
Love and tolerate.