Synergy is a measurement of the cohesion between a User and their controlled Character, displayed in the S-Meter at the bottom ride side of the game screen. As a User successfully lands attacks with their Character during battle, the Synergy will build and allow Characters to use special techniques that are otherwise unavailable. Synergy only lasts for the duration of the battle, resetting during transportation.
The S-Meter shows how much Synergy a User and Character have accumulated during the course of battle. When the meter is full, the Character will be able use a special attack or ability. Losing Synergy will prevent the user from using their special until the meter is full again. Every time a Character uses their special attack, the Synergy between them and the User will "Rank Up!" and give the Character a small attack modifier. Each time a Character's Synergy ranks up, their S-Meter will change color and reset. Synergy can rank up 6x before hitting maximum capacity.
Synergy is gained by landing various attacks on the enemy and lost when a character is struck by an attack. Each attack has it's own amount of Style gain, so not all attacks will generate the same amount of Synergy per hit.