HotShot is a tech used in Chrono Cross. To obtain the 'HotShot' tech, finish the events at Chronopolis. Kid will be at Hermit's Hideaway (Another World) at this point, but is unconscious. Use the Chrono Cross or Mastermune to enter her past. In the first room of this place will be a large machine by a burning clock. Pressing buttons near its front gives off a 'ding' sound. Press L2, Triangle, R2, and Triangle to get it. It is worthy to note that if you input the code too quickly, it will not register. You must hear the 'ding' after each button pressed. Thenceforward, Kid employs the lethal machine invented by Lucca to shoot molten projectiles at a single opponent.
Hot Shot is a word often used for a person with an inflated view of themselves. Its use here appears to be a pun of that colloquialism that also employs the literalness of the machine's ability to shoot warm projectiles.