Discharge and Heat Wave are already good moves, but opting to go without either of them can be painful, since they hit much harder on a lot of fields, and allow you to (somwhat) control where you are fighting. Of course, those aren't underrated outside of Reborn, so...
Magic Coat definitely gets props, especially since Luna walks into it every time. Not as useful as its ability form, but certainly good enough to hold in a fourth slot.