Just observing, I noticed some really interesting things about the designs of most of the pets:
1. Leaf Deer is the only pet who's head shot icon is looking in a different direction than how she normally looks. Normally she faces forward (like everyone else), but her headshot has her facing the viewer. Sure the cats kind of face the viewer too, but they're always facing the viewer.
2. Gladiator Horse is the only pet (though I can't test the Grass version) who doesn't freak out when picked up. In fact, he's crossing his arms and glaring like he's ready to destroy whoever he lands on. I don't have a Universe dragon yet, but if HE freaks out being picked up too, then Gladiator Horse is the most Badtail Kung fu pet right there.
3. Fire cat, Universe Dragon, and Dark Sabertooth are the only pet with normal paws that stands on their toes. The birds and horses do stand on thier toes because of the natural design of their feet, but every other furry and reptillian pet stands plantigrade, with their entire foot on the ground.
4.The pets are COMPLETELY unfazed by running on a log on LAVA at full speed. I think Leaf Deer's expression on the log sums it up best. She's all like, "Lava? Hmph...Mei must be on a tight budget this year." (Amusingly, My Leaf deer has survived fire hits and the revenge kill is SWEET!)
5. Leaf Deer, Shopoholic Cat, Rose Fox (though very hard to tell), and Oddet Swan are the only pet who wear close toe shoes. Flower Frillzard and Ninja Turtle wear open toe shoes. Everyone else is bare pawwed.
6. Tundra Reindeer and Firefrost Unicorn are the only male pets who have distinct eyelashes. They're also the only male pets to have some kind of eye shadow effect (though it's hard to tell with FireFrost Unicorn. All females have some eye shadow effect except Cheerleader Canary (though Fire Cat's is very similar in color)
7. Flower Frillzard is pretty Awesome in that she non-chalantly strokes the sharp side of her blade with her fingers and doesn't even bleed (but her opponent will).
8. Candle Weasel reminds me of Sideshow Bob. Gladiator Horse's Juvenile form looks like a Megaman Robot Master, and Antenna Giraffe looks like Melman from Madagascar.
9. Every Pet uses a different actual fighting style. Some based on chinese or Japanese arts, some based on European arts. There's also the Canadian Tundra Reindeer, even if they all wear chinese warrior based clothing.
10. The first pet you get, the Forest Lizard, makes the most gold per hour of all pets besides the Universe Dragon himself, but he's restricted to the Forest habitat, that holds the least gold. With the forest booster, he can generate almost 100 gold a minute at level 10.
11. I remind everyone, the BOOSTERS DO STACK! and they affect the PET'S element, NOT the habitat like the game claims.
12. I gotta admit, Leaf Deer is the reason I spend so much time playing this game with Flower Frillzard and Fire Cat being close seconds. <3 They're just so wonderfully designed and really capture my eyes, as well as their personalities. (The "Breaks hearts and bones" thing on Leaf Deer's description is what really sold me.)
13. It's FrilZard, Kao....there's a Z in there.
14. Half of the pets seem to smile when they get knocked out in the arena. This is especially noticeable with Mini-Me Dragon, and Ice Penguin, among a few others.
15. NEVER switch out in an arena fight. You need EVERY turn you can get an attack in and sometimes, taking damage may cost you a much needed pet. Even if you switch to a pet who you know can resist all of the opponent's elements, their physical attacks can still usually do at least half health if you're at the higher levels.
Whew, okay, I'll probably find more, but any other oddities or interesting trivia that anyone noticed?