Depends on the game.
Nintendo has five Wii games currently published that won't hit a million worldwide. Eyeshield 21 (100-200k WW), Donkey Kong Bongo Blast (500k-700k WW), Excite Truck (500k-700k WW), Fire Emblem may break a million, it may not, Forever Blue (500k WW).
On the Cube, tons; Battalion Wars was 50k in Japan and did less than 150k in its year of release in the US. DDR Mario Mix. Giftpia, obviously. Donkey Konga 2, and definitely Donkey Konga 3. Chibi Robo is pretty unlikely to have hit a million. Doshin the Giant, Nintendo Puzzle Collection... Custom Robo is probably around a million but less, Wario World same deal.
DS; True Swing Golf, Magentica, Electroplankton, Magical Starsign, Custom Robo Arena, Polarium, Metroid Prime Hunters probably, I can't imagine Picross will hit a million, Trace Memory, Hotel Dusk is probably under a million, Nintendo Magic, I can't imagine with the bad reviews and only 250k or so in Japan that Wario will hit a million, obviously all of Japanese only releases...