Lucca is clearly the brains of Chrono Trigger. In the game, she proves key to the story with her variations inventions and designs from the singing robot Gato, to the disaster that began Crono's adventure to save time to begin with. Unlike Marle who is a curious character, and Crono, who is brave, Lucca tends to look at everything with a more logical perspective and most of the time back-ups whatever she argues about with the party using science. It is also notable that if it wasen't for Lucca, Robo would've never joined the Crono's party when the group find him in a wreckage during their journey through 2300 AD. It also becomes apparent by playing the game's side missions that Lucca has motives of her own using time travel.
Weapons and Techs
Lucca is the only playable character in Chrono Trigger to use a gun, which is her main weapon in normal attacks. She also uses a hammer which can be seen when she uses any of her tech attacks. Although she fights notably weaker than other characters, there are many advantages to using Lucca over any other character. For example, she has some fairly interesting techs including a protect tech that can save people from physical attacks and her array of fire attacks that prove to pack some serious punch in some fights. Of couse, it would be better to use Lucca for Dual and Tri Techs whenever necessary.
At the begining of Chrono Trigger, we learn that Lucca is an avid inventor who likes engaging in fixing and making all sorts of machinery. She invites Crono to test out her new devices, at the millennium fair. These include Gato, a singing, fighting robot and a teleporter. Even before the teleporter goes into action, we learn that it has been functioning oddly anyway, but the real mess up happens when the teleporter reacts to Marle's pendant, which causes the gang to go back in time to 600 AD. Later on in the game, we're presented to Lucca's technical skill in the form of Robo, a robot Lucca decides to fix during Crono's adventure into 2300 AD. In the PS1 version of Chrono Trigger, there were special anime FMVs. In the final FMV of the game, Lucca is seen on a walk with a mino robo, and she finds Kid as a baby under a tree wrapped in a blanket. According to the story of Chrono Cross, Lucca takes Kid home, and cares for her by starting an orphanage. Lucca is killed by Lynx and Harle when they set fire to her orphanage in the year 1015 A.D.