For the entire battle, Saryu alternates between two abilities: a physical combo that deals around 400 damage and a multi-target Earthquake attack, which hits everyone for around 700 damage. When Saryu's HP is lowered enough he will use the technique Jugger Power, which boosts all of his stats significantly and makes him far more dangerous. This makes his physical attacks now hit for 800+ damage and his Earthquake do about the same amount as his physical.
Saryu's attacks are all Dark element, despite looking like Earth, and so Ebony Jewels are highly helpful in this battle. Defender Chains can also help soften the damage from Saryu's physical attacks, especially after he uses Jugger Power. If Vahn and / or Gala were able to absorb Kemaro from the mini-boss battle beforehand, then the fight becomes significantly easier. Otherwise, magic should be reserved for healing spells like Orb. Also, make sure to have some Phoenix items on hand just in case.