One of those really rare and hard-to-get pets. like the thunder hound or the two-headed dog thing. Oh, and I also like the heckhound. it took us FOREVER to get enough money to buy it. SHEESH! Did you know storm hound is also an actual move? I'm not sure I know what it does, though..... but someone will (hopefully) reply to me, because it would be the first time someone has. This is one of my first messages. :D Also, the pet heckhound does NOT give you the move. Same thing for bloodbat, storm serpent, etc. There are also a couple really rare, huge dragons that are pretty cool. You have to get them specially from codes or something. But the've all expired, that I know of. I also like the piggles that are ugly but give you health. Also, those pets you can get only by being a certain type. Makes me so JEALOUS!
Overall, the rare, cool, pets are the best. P.S. Please reply.
Yes, alot of pets are cool but the coolest one i think is the Life Cyclops. Wait maybe. But, still the pets that i think are the coolest i have made into a list here! Enjoy! :P
5: Danger hound 4: Ghost hound You can see I like the hound family! 3: Icezilla Don't know how to obtain this but it is cool as i have seen it! 2: Ninja pig easy to obtain but i think having a ninja pig is AWESOME! :D 1: And my favorite pet of all time and the coolest is: Magma Collosus ya there is one! If you've never seen it talk to Diego the Duelmaster on Unicorn Way. Than click on pets and it will be the last one! Now it is a lot of arena tickets but its worth it! Thanks for reading hope this helped!
Talents - Fierce Hound and Sea Dragon Looks - Firewalker and Reaver Given Spells - Ianthine Spectre and the cyclops pet that gives Regenerate, I forgot its name
This is simply my OPINION, you dont have to go crazy about what pets I prefer.
The Dragon and Piggle are the most fashionable pets, I'm sure, but they're actually pretty weak.
I'd say, that the most recent pets that came out are among the most powerful. The Sea Dragon (Obviously), followed by the Spinyfish, Sea Turtle, Jellyfish, Fierce Hound, and then followed by Flamezilla, Burnzilla, Ice Hound, and the Gift Card pets (When redeemed in December so they have Dragonblade and High Pedigree)...And then followed by the Level 48, School-Only pets.
My favorites, though, will always be the Mander and Rat Magician(s). Sure, they're terrible and give weak cards (Or no card in most cases), but are tall (for a pet) and look awesome. They seem more like a little sidekick to me than a pet!
I am more a fan of those rare rare rare SUPER RARE pets you get from bosses. My favorite out of all of them is the fire serpent (obtained from boris blackrock ((AN ICE ENEMY!)) in Dragonspyre).
I think that the fairy is the best because it gives you 480 health healing card and it is very rare I'm guessing because I had people come up to me asking where i got my pet (the fairy) and i told them i won it in a battle in MB.
Wait maybe. 
But, still the pets that i think are the coolest i have made into a list here! Enjoy! :P