your answer is in the question - elemental dmg. Anko + FM both do elemental dmg + Iruka boosting and giving shield + Asume WB and boost the fire ninjas with the fm skill, 10combo chase from main aswell as from iruka. The boss is also weak to specific type of ninjas like yamato that deals more damage on the 9tail because of the passive. + the unparalleled talent gives ur main extra dmg boost vs summons/clones etc.