Hunter Pets  

There are two main pet categories to think about when obtaining a pet for your hunter, DPS and tank. There are also hybrid mixes and the often misunderstood "casters". To some, this knowledge comes instinctively and to others, it takes actual experience with each pet family/category to fully understand their roles as the hunter's partner-in-crime.

DPS

DPS pets have a higher potential to deal more damage than other pets, but they also can be a little less able to withstand the heat of the battle if they become the focus of your enemy. Many PvPers prefer DPS pets as while in battle, your pet is usually being ignored while you are the target, thus your pet's ability to bring on the pain.

Tanks

Tank pets have quite a bit more longevity when they are in battle with an enemy, whether your opponent is in arena or you are helping a group with an instance boss. These guys are like a big brother and have the ability and often do, take a lot of heat while the two of you work in unison to pack quite a punch. They are a popular choice while leveling as they do not have as many problems surviving higher level enemies or several mobs at a time.

Hybrids

Hybrids are a jack-of-all trades, quite tough and decent at throwing out damage, but masters of neither. They are good pets for players that want one pet that is able to multifunction in several situations.

Casters

These guys have higher than normal intellect and spirit, but this comes at the expense of their health, attack power and armor. When as a young hunter you first obtain a caster pet (these are usually the pets with a mana bar) you may be in awe and think that everyone was wrong in characterizing their powers as weak simply because the differences in the health, attack and armor stats aren't seen quite as readily when they are youngins'. At later levels; however, you will notice that the stat levels play catch up and your pet doesn't seem quite as up to par as DPS Moe and Tank Joe who are currently stabled.

Rare/Spawned

For some hunters, they want that pet that no one else has. That elusive creature always whispered about, yet never seen. These rare and spawned guys often fall into either the DPS or tank categories and as such should not be looked at as a myth. It may take you on an adventure to the side of having to somehow try and communicate with the other faction, a six-hour long stakeout or treks into instances that require help from friends.

To see a complete list of pets, their attributes and tamed/learned abilities, please check out Petopia.