Wild Pets can be found throughout each continent, some being more rare than others. To collect one, you’ll need to engage it in battle (with one of your current pets), successfully capture it and win the battle if there are more than one to a team.
Here are the unique wild pets for each Cataclysm zone.
I couldn’t seem to find anything in Vashj’ir but will update when I do.
Pandaren Champions can drop a satchel (containing linens, jewels or skins), a piece of armour as well as a special item. These had no novelty items attached to them.
Found on the outskirts of Ambermarsh
At the top of a hill around Sik’vess Tree
Patrols Fire Camp Osul
Standing by the little camp at the west end of the wall
At the top of a hill, north of Shadow-Pan Garrison
Found in the ravine between Townlong Steppes and Dreadwastes
Found in a cave of the Lower Sumprushes