So my daughter just appropriated my GameBoy Color

[ethinethin]

I always enjoyed Mario's Picross. The puzzles are kind of like Sudoku, except you end up drawing pixel art.

[sevin0seven]

she might like Barbie: Game Girl for the Game Boy....not sure if you do.

[Hazerd]

I also vouch for Donkey Kong '94, great game, also check out
Teenage Mutant Ninja Turtles: Fall of the Foot Clan, it has bonus puzzle stages you can find during the levels that are fun!

[noiseredux]

Hexcite is my favorite GBC puzzle game.

[Zing]

My six-year-old can "play" Link's Awakening but isn't able to progress very far. How old is the OP's kid? Four? I can't imagine them getting far in a game like Donkey Kong or Super Mario Land.

What about something like Boxxle?

[RyaNtheSlayA]

She should be able to enjoy classic arcade games. I'm not familiar with the GameBoy but considering it's popularity I'd assume there are at least a few. Simple and fun.

[GameMasterGuy]

What about one of the Game & Watch galleries?

[Nintendork666]

Maybe she'd dig a Gameboy Camera?

What about one of the Game & Watch galleries?

^ This too.

[Hobie-wan]

Bomberman (various)
Mole Mania
Uno

[The Nihilist]

Oh man, didn't expect so many responses. I'm looking up youtube videos and looking up game reviews for everything everyone listed. Few things!

Pokemon Pinball.

I got a good laugh because I just sold the game. But man, that game to me is visually overwhelming.

Tetris Attack! Learning curve but amazing puzzle game.

This is the missus favorite game for Super Nintendo, I think she might explode into wife-dust if I tell her that it's on gameboy.

Pokemon Puzzle Challenge might be more fun than Tetris Attack if she recognises the characters.

I think her extent of Pokemon was a toothbrush she saw at a store and adamantly swore up and down that Pikachu was a bunny.