It's no coincidence that your pet occupies an equipment slot; the companion pet (besides looking cute and often having customizable colors) can offer a wizard enough boost to be the deciding factor in closely-fought duels.
So for this post, I'm going to pay a little attention to the little critters in our wizardly lives!
First, let's talk about Spritely. It's a pet ability that only a few pets have, including the new Brave Hound rewarded for the Facebook sharing virality campaign. Spritely is the pet ability to occasionally cast sprite heals during combat. This is not a spell card given by the pet and added into your deck; this is the ability to cast in addition to your casting. This additional cast means you don't have to spend extra time casting yourself... in effect, you sometimes have the ability to cast more than one spell in a turn. In some rare instances, three times in one turn (two sprites in one turn - I've seen it happen!). I've often envied those players with sprite-casting pets. Not having to worry quite as much about healing allows you to keep your planned sequence of casting, which can be very important if you are timing your spells to go off before an anticipated spell or effect from your opponent might go off. Though it's not guaranteed that your pet will cast one or more sprites, it happens fairly frequently; and when you consider the number of battles that you were one more spell away from winning, it's easy to see that one free sprite cast might have made the difference. However! Since I didn't know too much about pets, I always assumed that any pet might be able to learn this ability, and that it was just rare luck or purchased pets that got this. I was wrong... only some pets get the chance to learn. For those who don't know, here's a list of all the first generation pets (I think!) that can learn the Spritely ability:
Assailing Dragon, Brave Hound, Cupig,
Evil Sandman, FOG Unicorn,
Fiendish Foo Dog,
Fierce Hound, Forest Lord*,
Ghost Dragon,
Giraffe,
Guardian Foo Dog, Humongofrog*, Ice Wyvern*, Jellyfish, Judgement*, Kraken*,
Night Hawk,
Patriotic Leprechaun,
Pet Egg, Phoenix*,
Samoorai, Satyr*, Scarecrow*, Sea Dragon, Sea Turtle,
Snake in a Basket, Spinyfish,
Spirit of Nature, Starfish, Utility Dragon, Vigilant Dragon.
There are hybrids and second generation pets that can learn it, but I'm not too knowledgeable at this pet hatching thing yet. Pets in italics are crown-purchased only pets. Pets with asterisk are school-awarded pets.
Second, the other abilities and how they help you out. I have a low level Conjurer who is wearing gear that boosts his Myth accuracy by 4, leaving him at an 84% accuracy. I gave him a pet Minotaur I found with a higher level character (drop from Youkai near end of Mooshu) and trained him to epic. He gave a +6% bonus to Myth accuracy. So while that pet was equipped, my Conjurer had the same accuracy as your fresh Theurgist at 90%. That was a big boost, and made for some great low level adventuring. With the recent Brave Hound addition, though, I now run around with Spritely for my guy. My dog is not yet epic, so I'm hoping to recapture that accuracy bonus, so I can leave my Minotaur to guard the gates of my house :)
Pets have a real and intrinsic value that can add to your character's strength. It's no wonder that players will hatch new pets to try and get the ability that their last one lacked.
Which stats boost what ability (max seems to be +6%, and maybe max 2% per ability, requiring three abilities to boost).
(school)-Giver, Add-Balance (Strength, Will, Power), bonus school damage
(school)-Proof, Unbalancer (Strength, Agility, Power), bonus school resist
(school)-Shot, Balance-It (Intelligence, Agility, Power), bonus school accuracy
Pip-O-Plenty (Strength, Intelligence, Power), bonus power pip chance
Sharp-Eye, Sharp Shot (Intelligence, Agility, Power), bonus universal accuracy
Spell-Defying, Spell-Proof (Strength, Agility, Power), bonus universal resist
Pain-Giver (Strength, Will, Power), bonus universal damage
Health Gift, Health Bounty (Agility, Will, Power), bonus wizard health
Mana Gift (Intelligence, Will, Power), bonus wizard mana
I'm searching right now for the site that will help you determine how your pets ability stats will affect the strength of their talent. Oh. Here it is:
http://petnome.pbworks.com/w/file/fetch/46870777/Petnome%20Calculator.pdf
As a matter of fact, it looks like this site is just generally useful in pet lore (so here's the link to the home page):
http://petnome.pbworks.com/w/page/27388686/Home
Also, someone went through an awful lot of trouble in experiments to help you if you should want to make a designer pet (careful long breeding program!):
http://wizard101.wikia.com/wiki/Creating_a_custom_pet
So! With all those words above, what to make of it all? What do you want your pet for? Looks? Then google that pet, find out how to get it, and if it requires farming for it, then keep killing that boss until it eventually drops. If you want it for the pet derby... I don't know. I don't play that part of the game, so I don't know which abilities are awesome or not, but if you find out, then get the pets that have that ability (or abilities) and keep training them and hatching similar ones. If you want to get pets for their abilities, google which abilities you like, find which pets have them, and go after them.
School pets tend to be very powerful, but you will be pretty far up in level by the time you get them. I notice that when you hatch your new pet, it will often have the average pedigree of its parents (so if one of your parents' pedigrees is low, it will likely bring down the pedigree of your pet, though this doesn't seem to be an exact science). Your newly-hatched pet will more often than not be the same kind of pet of the parent that had the higher pedigree.
Alexander has a Phoenix that is now Ancient, with only one talent left to uncover, I can say that I likely won't bother hatching a pet from him to get something else, because he's give me good stuff! He's given me two "may cast:" abilities of sprite and fire trap, and also Fire-Giver for extra fire damage percentage. My hope is to get Fire-Shot as well for accuracy, but if I get a pet-centered ability talent, I'm hoping it boosts the phoenix' strength, will, or power to increase his damage bonus.
If I were to farm for a pet, it might be the Sea Dragon, which has a chance at Spritely AND Pain-Giver (universal damage bonus). Any pet that can be useful to every school makes me happy. And he's one silly looking pet, so your wizard will travel light in heart.