Squirt is, bar none, the fastest way to level pets in bulk at a relatively good pace. There has been faster ways of doing it, but those were nerfed to the ground ages ago (RIP JSA!).
For the tactics I use, you'll need an S/S Bronze Whelpling (ie. it must have a speed of 325 at level 25) with Tail Sweep and Early Advantage, Widget the Departed with Spectral Strike and Prowl, and the pet you want to level.
Start with Bronze Whelpling
Against Deebs:
4x Tail Swipe, which will kill Deebs
Against Tyri:
Early Advantage
Your Bronze Whelpling will be killed by Tyri's Call Darkness, so swap in Widget the Departed:
1x Spectral Strike will then kill off Tyri
Swap in your carry pet, since Puzzle will always cast Dodge as his first move, so the carry will take no damage at all. Then swap Widget the Departed back in and use Prowl followed by Spectral Strike, which should one-shot Puzzle.
The fight is now over, so walk a few steps backwards to the Stable Master and rez & heal your battle pets and go again.
Edit: The whole fight is also spelled out in details here:
http://www.wowhead.com/npc=79179/squ...nts:id=2311049