Nintendo DS Recommendations.

[Kenryoku_Maxis]

Of all the games I have played for DS, these are the games I suggest the most:

Dragon Quest V
Dragon Quest Monsters: Joker
Dragon Quest Heroes: Rocket Slime
Chrono Trigger DS
Pokemon Diamond/Pearl/Platinum
N+
Space Invaders Extreme (Import Joystick available)
The Legend of Zelda: Phantom Hourglass
The Legend of Zelda: Spirit Tracks
Kirby Canvas Curse
Kirby Squeak Squad
Kirby Super Star Ultra
New Super Mario Bros
WarioWare Touched!
Ninja Gaiden: Dragon Sword
Henry Hatsworth in the Puzzling Adventure
Osu! Tadakae! Ouendan! (Import)
Osu! Tadakae! Ouendan! 2 (Import)

Personally, I'd say the 5 best DS games I'd recommend aside from the ones you already have are:

Dragon Quest V
Kirby Canvas Curse
WarioWare Touched!
The Legend of Zelda: Spirit Tracks
Osu! Tadakae! Ouendan! (if you can import it)