Strand Crab

I got mine joining dragonbone hatchlings out in Dragonblight

Two in a row joined battle with Maggots in the Fire Scar Shrine in SW Ashenvale.

This pet is my #1 pet so far. Great for leveling other pets when it hits 25. Combination of the sheild (c-ya later dots!) and healing is great for not having to bandages or revive after battles. I highly recommend finding a rare Shore Crab, Strand Crab, or Strand Crawler to help with leveling other pets. I has even become an all star in pvp pet battles.

This pet is also found on the Zoram Strand in far western Ashenvale, often as an adjunct to the Rusty Snail (lvls 5-6) fights.

This pet is effectively the same as the Strand Crawler in terms of stats and abilities; in fact, a Rare version of this pet is exactly the same except in terms of looks.  Suffice to say, a rare one of these is a very resilient pet, and a solid choice to have as part of your core team.

Currently, this pet is my best one and first one I leveled to 25.  It's a good pet to have while leveling your pets; it can tank (if that's appropriate to use in pet battles), self-heal, and provide support healing to your other pets.  Since I'm still only collecting pets, I'm currently still using this guy.  Downside is its weakness to flying and its speed.

Got one in Dragonblight as secondary pet from Dragonbone Hatchling.

They are also available in Borean Thundra and are ~lvl 20

I could never find these just milling about in Ashenvale -- the only way I've seen them is partnered with other wild pets. Hopefully this will save you guys from flying around Ashenvale with no luck.