Let Tidus have a thunder weapon and wakka have a ball that has thunder or that has darkness.If u let wakka attack it with a darkness weapon the Extractor will miss its attacks .Let Tidus attack and heal when need.try to have wakkas overdrive full so u can get the at least 2 lightning to help.If it is ready to do depth charges be sure your character is healed all the way.When it did do depth charges then heal.Before it does depth charges it goes up let wakka attack while tidus heal them fully when tidus is done healing let him help attack.