You get Paine's special dressphere during Chapter 1. Find Tromell at the Macalania Woods and sneak to him four times and the dressphere is yours. The three portions of Full Throttle act as a three-member party. Some portions can cast protective spells on the other parts, and each can inflict devastating magic attacks on enemies. To use Full Throttle more often equip Paine with the Unerring Path Garment Grid, which only has 2 dressphere nodes. This makes switching to Paine's special dressphere much faster, since she only needs to change once before transforming into Full Throttle.