Help me choose...

[Ethlin]

Alright, I need help choosing a good team. I am not going to go hard-core pet battle PvP, but I would like a *decent* team for the times I do. There are a few things that I want to keep my team to...

~Can not be Blizzard store pets. I am not spending IRL money on anything other then the game sub.
~Must be obtainable (For example, no promotional stuff like Blizzcon/CE Pets/etc.)
~Only picking ones I like (For example, I don't care for generic squirrel #1256237, more info below)
~I am too lazy to make gold, so I can't buy any stones to upgrade pets with, meaning they must start rare.
~Feel free to mention an uncommon pet worth upgrading if I happen to get lucky and come across a stone myself.

Humanoid

Harbinger of Flame and Feral Virmling are the only (rare) ones I have atm. I run old world raids a lot, so my chances of getting the others are decent, so keep those in to account. Which of these would you recommend (Keep in mind the other old world raid ones as well)?

Dragonkin

I have a good amount of these and I am fine using any of them. Any recommendations about this? I can also catch later ones after I level my early pets.

Flying

I like the Sporebat and Hyacinth Macaw, are either of those good or should I search for another, if so then what should I try to get?

Undead

Must be a Naxxramas pet (Inside joke with me and some friends), I like the Mini-Loatheb in the early levels, but I am not sure how well it would scale. Of the three here, what is your recommendation?

Critter

To be honest I has never a fan of these : / I like the snails (I got a rare Rusty Snail) and the Giant Sewer Rat, but I am not so sure how well they perform. How are these ones? If they all suck, what should I look for?

Magic

My only rares are the Disgusting Oozling and Shimmering Wyrmling. I prefer the oozling, but I also like the other, so I am not opposed to using it if it's better in battle.

Elemental

I got a lot of rare ones of these, I like the actual elemental ones (Pebble, Searing Scorchling, Tiny Twister, etc.), which of those are the best? I am also not opposed to using the Phoenix Hatchling, Sinister Squashling, or Crimson Lasher.

Beast

I got a lot of these as well. I prefer spiders and snakes but am not opposed to other types. Any recommendations here?

Aquatic

I got a few of these. I like the crocolisk ones, but I hear Mr. Pinchy is extremely powerful in combat. I am not so sure about this one so I am open to any suggestions at all.

Mechanical

I only have the Clockwork Gnome, Darkmoon Tonk, and Darkmoon Zeppelin, none of which I care for actually. From what I understand the Clockwork Gnome is really good, so I might go with that. Also I was going to search for the Fluxfire Feline, but it's getting nerfed next patch and I am not sure if it's worth my time finding a rare one now. Also I like the mini-harvesters in Westfall, so I can find a rare of those if they are decent.

Thanks ahead : /

[Zaelo]

Took a quick look at your list and I'd recommend the following:

Celestial Dragon (you didn't specifically mention you had this one but if you don't, he's not that hard to get, and is totally awesome for leveling)
Clockwork Gnome (you don't seem a fan of this one but he's easy to level as well, Repair + good dps)
Disgusting Oozeling (good dps and life leetch, will be nice to level too)

You mentioned Mr Pinchy, which is actually an item that can drop Magical Crawdad, but if you can get your hands on him, yes go for that one too (replace the Gnome or Oozeling).

Also Molten Hatchling, once you get high level enough to hunt one down, go get a rare ones (in Searing Gorge I think), once at 20 he's more than worth it.