Game Boy

A blue Game Boy Color system.

Game Boy was the first handheld developed by Nintendo. While the original system displayed games in black and white, the later Game Boy handhelds, Game Boy Color and Game Boy Advance, allowed for a color display.

Enix and Square Enix released several Dragon Quest titles on Nintendo's various Game Boy systems.

Game Boy

No Dragon Quest titles were released for the Game Boy; however, Dragon Quest I & II and Dragon Quest Monsters were backwards compatible with the system. Both games could also be played on a Super Game Boy, an adapter that allowed games to be played on a Super Nintendo Entertainment System.

Game Boy Color

The Game Boy Color is the successor of the original portable Nintendo video game system, Game Boy, and the predecessor of the Game Boy Advance. It is notable for being the first handheld to feature a full 15 bit color palette, of which up to 56 colors could be displayed simultaneously.

Dragon Quest titles for the Game Boy Color

Dragon Quest I & II - a remake of the first two games from the Nintendo Entertainment System with updated graphics. Backwards compatible with Game Boy system. In addition, this game can be played on the Super Nintendo Entertainment System with the Super Game Boy cartridge.
Dragon Quest III: The Seeds of Salvation - a remake of the third game from the NES with updated graphics and added bonus dungeon. Required Game Boy Color system (or Game Boy Advance) to play.
Dragon Quest Monsters - the first monster taming game with a young Terry from Dragon Quest VI: Realms of Revelation as the hero. Backwards compatible with Game Boy system. In addition, this game can be played on the Super Nintendo Entertainment System with the Super Game Boy cartridge.
Dragon Quest Monsters 2 - released in two versions, "Cobi's Journey" and "Tara's Adventure". Both versions can be played on the Super Nintendo Entertainment System with the Super Game Boy.

Game Boy Advance

Game Boy Advance (ゲームボーイアドバンス, Geemu Boui Adobansu) is a 32-bit handheld video game console developed and manufactured by Nintendo. It is the successor to the Game Boy, and was the Dragon Quest series's preferred handheld platform before the Nintendo DS.

Dragon Quest titles for Game Boy Advance

(These three games can also be played on the Nintendo DS and DS Lite.)

Dragon Quest Monsters: Caravan Heart
Slime MoriMori Dragon Quest - the first slime spin-off game.
Torneko no Daibouken 2

Note

A characterized version of the Game Boy unit was present in the 2nd and 3rd seasons of the cartoon series Captain N: The Game Master, which had a couple of episodes based on Dragon Quest.