[Shilenne]

The water elemental rank 1 is a caster dps. It's the only caster pet atm (so it doesn't chase the mob around it stands at a spot and shoot at it). None of the pet has "skills" on its own, only the basic attacks. It's the spiritmaster that controls what it use. So far at lvl 19 I have heal, buff pet defense, increase next attack, and "taunt".

I'd say the pets go something like this.

Treant is the "tank" pet, it has the most HP, and most defense, its attack is fairly weak, and because of that as of now it doesn't hold aggro decently against me :P.

Fire is the "tank and melee dps" pet, it has the second most HP, not as much dodge as the wind pet, and it hits pretty hard. But since it doesn't dodge as much as wind pet, most people uses wind pet to dps normal mobs (so they have to heal it less).

Wind pet is the dps pet, it dodges attacks kinda nice, it has slightly less hp than Fire elemental, but hits slightly more. I use this when I'm soloing mobs before I got the water pet, I'd recommend this to most people if they're not a fan of kiting things around while pet dps in 1 spot.

Water elemental is the caster dps pet, it has the least hp (less than wind pet) and from how much things were hitting it for, i'd say the least armor as well. But it deals the most dmg, and it stand still (doesn't melee). I'm very lazy when it comes to healing pets, i prefer not to heal it at all (because heal pet is on a 1 minute cd, and so far it doesn't scale so well). So what I do is I try to dps it enough so the mob comes running after me while the water pet cast at it while the mob's chasing me, with the improved attack the water elemental will kill it pretty fast, but it might pull aggro from me after a while. So I slow the mob and usually the water elemental will kill it before it can touch the elemental at all. I'm pretty use to playing kiters though, so I can see how people wouldn't prefer this way if they weren't kiting.

Also, I was using the wind pet when I was fighting elite mobs (especially archers, I los them then jump out to use a pet skill and then hide again behind the rock). Usually people would use fire elemental, especially because they get rank 2 of it at lvl 22, but I was being lazy and I'm impatient so I like killing mobs fast. As for elite melee mobs, I used Water pet instead and played Monkey in the middle with the mob (pulling aggro with my pet then myself etc so it doesn't really hit either of us).