The DS was such a fantastic console with so many games on it. My top 5 were:
1. Pokemon Mystery Dungeon: Explorers of Sky
2. Dragon Quest IX: Sentinels of the Starry Skies
3. Chrono Trigger
4. Mario and Luigi: Bowser's Inside Story
5. Pokemon Black and White 2
Other games that I enjoyed were: Super Mario 64 DS, Dragon Quest IV-VI, Mario Kart DS, Pokemon B/W, Pokemon HG/SS, Pokemon D/P/Pt, Nintendogs, Pokemon Mystery Dungeon Blue Rescue Team, Pokemon Mystery Dungeon: Explorers of Sky/Darkness, 999, Fire Emblem: Shadow Dragon, Mario and Luigi: Partners in Time, New Super Mario Bros., Phoenix Wright: Ace Attorney, 999, and I could go on.