The latest Pokémon games in Japan, HeartGold & Soul Silver, sold 1.4 million copies (1,408,980) in the first two days they were released. The highly anticipated remakes of the original Pokemon Gold and Silver were released on September 12th.

As a bit of Déjà vu, below is a press release from the American launch of Pokémon Gold and Silver. It sold almost the same amount of copies during its launch week.

REDMOND, Wash.--(BUSINESS WIRE)--Oct. 23, 2000
Pokémon is hotter than ever. The latest games featuring the world's favorite kid entertainment phenomenon, Pokémon Gold and Silver for Game Boy(R) Color, sold an astounding 1.4 million copies in the first week of availability, smashing industry sales records. The previous U.S. record breaker, Pokémon Yellow(TM) for Game Boy, sold just over 600,000 units in its first week.

Sources: http://mainichi.jp/enta/photo/news/20090914mog00m200034000c.html & http://www.encyclopedia.com/doc/1G1-66267473.html