Rookie Pet Group

You may be asking yourself: "What's to stop me from capturing level 9 creatures to minimize my effort on this one?"

The answer: Nothing's stopping you. It works.

It may be worth noting it says raise, so capturing 15 lvl 10 pets will not grant you the achievement

A quick way to do this if you have a couple of pets in their twenties is to fight Dragonbone Hatchlings near stable master Risera in Dragonblight so you can go from level 1 to 10 in 8 fights (or if you have level 9s already 2 fights).

If you want to get fancy too, park another toon in Stranglethorn vale near the level 9s. Capture 3, log out and in to the character in Dragonblight, level them to 10 using that location, release them and repeat.

I wrote more about this technique in this post.