Actually, it's Fire > Ice > Fire and Light > Dark > Light. Fire and Ice are opposing forces, and so are Light and Dark.
But this is assuming that you'll always find an elemental monster. For other things without a clear element:
Fire > Plant, Insect, Building, Armor
Ice > Human, Beast
Light > Undead, Demon, Spirit
Dark > Dragonoid
But even then, most of these are obvious. Undeads would naturally be Dark and weak to Light. Plants would obviously be weak against fire. The only obscure ones are the human and beast weaknesses. Then, there are Hybrid types, which will be one of the two above categories. Sometimes that means more weaknesses to exploit, but most of the time, the different strength and weaknesses could cancel out.
Last edited by Shadow5YA; 03-25-2010 at 12:40 AM.