Final Fantasy Crystal Chronicles

Final Fantasy Crystal Chronicles is an action role-playing game. Players take on the role of adventurers who travel in a caravan gathering mystical fuel for crystals which protect the world's settlements from the destructive Miasma. The single-player campaign has the player escort the vessel carrying the crystal's energy, defending it and solving puzzles to progress. Multiplayer, which uses GBAe units connected using the link cables, has up to four players protecting the vessel. (wikipedia.org