can help you get started.
I think Spell Cancelling is still in the game, so you could try to do that as Kratos or Zelos to rack up the hits.
As your party members, I would suggest Raine, Krats/Zelos, Lloyd and Genis.
Make sure you equip the weakest weapon you can find (the not unleashed devil's arms come to mind) and start hitting an opponent that heals when hit by a certain element (like the Ice Warrior things with swords in Celsius' Temple).
Make sure that roughly each 100th hit is a Photon by raine. Normally enemies stagger at a certain combo count (around 100), but with photon they get stuck and the combo count continues. Alternatively, you can use hourglasses, which can easily be farmed with Zelos' Personal Ex Skill and two Rabbit's Feet equipped (make sure to take off the devil's arms for this part).
Whenever the ice warrior you're pummeling starts to run out of health, heal it with one of Genis' ice spells (go Strike for Ice Tornado and Absolute).
Lloyd can assist you in pummeling the Ice warrior with his 27 hit combo:
Sword Rain -> Lightning Tiger -> Sword Rain Alpha -> Raining Tiger Blade.
End the battle with the prisms stars Unison Attack.