Fire: Does single hit single target and aoe damage, have SP skill that ignites the enemies and do % damage on enemies, and have damage stat amp skill. (Usage: A niche usage considering your damage most of the time is gonna be blocked by enemies defense)
Water: Have medium debuff skills, SP skill which heals and negates a percentage of damage, and defense stat amp skill. (Usage: Not exactly sure other than the SP skill is great for defense of enemies special 100% skill)
Wind: Does multi hit single target and aoe damage, have SP skill that hits # of random enemies with agility boost, and agility boost stat. (Usage: Great for enemies with low defense considering it boosts the highest damage compared to fire, but will fall short if the enemy have high armor)
Stone: Does Single and later on aoe defense ignore damage, have defense increase skills, SP skill regens characters a certain amount of hp per turn, and have heath stat amp skill. (Usage: Pretty much your go to if you're behind on damage and want to chip away at enemies health, or the enemies armor is ridiculously high)
Holy: Does single target or aoe healing skills, single target attack buffing skills, SP skill recovers from debuffs and heal 30% hp, and have MP stat boosting skill. (Usage: Your go to for healing and strong buffs, but water SP skill could do the job also on top of damage neglect, so for high buffs and mana stat only)
Dark: Does single target space distorting skills, high debuff skills, and SP skill will do healing damage and later regular defense ignoring damage, and SP skill will increase space distort. (Usage: Not exactly sure what the space distort thing is about, but the debuff is really impactful in the game.)