Launch date: November 21, 2004
Lifetime sales to date: 154.02 million units
Nintendo's most successful console ever made, by a huge margin, is the Nintendo DS.
It was innovative — two screens! touch gameplay! a microphone built right in! — and ahead of its time. The iPhone didn't launch until 2007, and it was another year-plus before Apple's ubiquitous phone pushed into mobile gaming.
Gamers marveled at its impressive graphics, its innovative approach to design, and its mobility. It delivered on the promise of the Game Boy and upped the ante. It's no surprise that the DS is Nintendo's most successful console — in many ways it embodies the best aspects of Nintendo's business, all in one. It's unique, inexpensive, full of great games, and fills a need that most folks didn't know they had.
It also had "Nintendogs," which, ya know, dogs are pretty good.