This is your first hard boss fight. In the beginning, use Fire Whirl on a Bit. After about two Fire Whirls, the bit should be gone. Do the same on the other Bit. Now focus all attacks on the Guardian. Soon it will countdown from 5 to 0 and then launch two more bits. Continue the process. Save MP with Chrono and Lucca.
Lavos Form
When the players fight Lavos, it will have the same strength as the bosses you've faced in the past. One of them is Guardian (with bits).
