Ok this one depends honestly cause I've heard it's hellish without a friend and I don't think I know anyone who'd be willing to tackle this beast with me.
Ardy Lightfoot
Billy Hatcher and the Giant Egg
Densetsu no Starfy
Janken Disk Shiro
Kaze no Klonoa: Moonlight Museum
The Legend of Zelda: Link's Awakening
Metal Slader Glory
Mystical Ninja Starring Goemon
Nights Into Dreams...
Picross 3D
Rhapsody II: Ballad of the Little Princess
Ristar
Slime Mori-mori Dragon Quest 3: Daikaizoku to Shippo-dan