Dark Schneider: Nuker, but able to tank and melee in a pinch. His natural charisma makes him leader, even though he is a Bastard.
Lina Inverse: Nuker / Lore. She's In it for the gold and brings lulz to the party. Has knowledge of relics and lore that could useful in identifying items, structures, ect.
Raquel Casull: Nuker / Party defense. Level head of the party. Mother figure for the younger members of the party. Fast casting time and barrier are also a bonus.
Negi: Nuker / Melee. Powerful young mage, but he's definitely the person getting power leveled in this group, at least until he reaches full potential (see Dark Schneider).
Schierke: Nuker / Scout/ Elemental compass. She can use astral form to scout the area and has the ability to see the elemental nature of the target to coordinate nukes.
Konoe Konoka: Healer/ Refresh whore. Not that the group would need her for the healing, but the side effect of her healing was an excessive buildup of mana in the target; that'd at least good for some free nukes.