This pet is taught from Spiky Collar a random drop from one of the bosses The Big Bad Wolf in the Opera fight in the level 70 raid Karazhan. You do not have to battle this pet to receive it.He will be a level 1 pet.
This can be quite time consuming as the boss you fight in the encounter is random, so you have no guarantee each time you go in there and work your way to this fight that The Big Bad Wolf will show.
Karazhan is located in Deadwind Pass. This pet is part of the Raiding with Leashes II: Attunment Edition Achievement.
Lil Bad Wolf – Talents
As with all pets he will start out with his first talent and gain the others at levels 2,4,10,15,20