Okay.. Bascially, in a time of great need, a character can unlock a time-sensitive transformation unique to them (also available for battle items). This is called a "Cascade". Later on, they can activate it at will, if they've mastered it.
Anyway, the character's fur color changes or they get a special pattern added onto it. Their Hissatsu either changes completely or evolves (E.g. a fire character doing a Cascade might have a water-themed Hissatsu in the form, losing their fire abilities for a short time period).