Besides the link I sent, here are my personal faves that still hold up...
Tetris
Dr. Mario
Donkey Kong (includes 100 boards & the complete original game)
Super Mario Land 2: 6 Golden Coins
Super Mario Land
Metroid II (Best portable metroid until Metroid Fusion.)
Kirby's Dreamland
Kirby's Dreamland 2
Kid Icarus
Donkey Kong Land 2
Donkey Kong Land
Donkey Kong Land III
Mega Man IV
The Legend of Zelda: Link's Awakening
Wario Land: Super Mario Land 3
Warioland II
Bomberman
Pokemon - Blue/Red
Final Fantasy Adventure
Wii Code 3456 7941 4060 2924