Before you goto fight Dario, go and fight the Black Dragon. During the fight have Fargo steal from him. If you miss run away and start the battle over again. You should get the black plate. Equip it to your best character and give that person a LOT of curing elements. You should absorb all of Dario's techs. This helps alot during the fight.
Submitted by Freddy Cliver
After you beat the Time Devourer in all six of his forms, when you fight him the last time when hes ultimate, use the elements listed below in the exact order and use the chrono cross element and you will get the good ending.
Submitted by Jonathon & James