Earth and water have a weaker damage output because they're meant to support other party members. Earth is good at taunting damage away from party members; water can help strengthen and heal from damage. They're not really meant to be used alone.

Air, on the other hand, is also not meant to work alone since it has no healing abilities other than Mend... but it's a cannon element. If it had a weak damage output for you, you may have had a bad proficiency point/equipment setup. A well-built air pet can deal quite a lot of damage.

(That being said, shadow-fire-light all in a party together /would/ be a well-balanced party. But earth-air-light is equally effective.)

oh, cool :) thanks for the info ^-^

I tried a few different elements for a tank and I like Water for a few reasons, Frost protects the pet alleviating the burden a bit for the healer or at least gives the tank a chance to preserve its health while being healed.

Also it can buff the team while still being able to fight.

I considered Shadow as a tank but at low levels it is kinda useless.
I don't know..I might try building another team and try out different elements but water is a great buff at higher levels.