This page is a stub. Please consider contributing to it.
When the main and sub ally in the party leader, party member 1, or party member 2 slots have matching types, then the type match bonus will be displayed. The type bonus boosts the amount added to the sub ally's ST gauge each time the main ally attacks. Note that the boost amount will differ depending on the rarity of the currently subbed ally. If you switch between main and sub allies of different rarities during the battle, the boost amount displayed will differ.