I noticed something odd while battling Forest Spiderlings outside Lunarfall (don't know if this happens near the Horde Garrison as well). I currently have a level 2 Garrison. To the west of the Garrison, but still inside the Garrison zone, is a path down to the ocean where we beached the battleship after leaving Tannan Jungle. There are lots of Forest Spiderling wild battle pets in the area.
Initiating battle with a Forest Spiderling inside the Garrison zone causes it to fight alone, like the Arcane Eyes in Deadwind Pass. Initiating battle with Spiderlings just across the border into one of the regular Shadowmoon Valley zones triggers the usual three pet battle.
I have found this to be very helpful for leveling up pets -- I'm still working toward my first level 25, and it appears that beating a lone Spiderling awards the same pet exp as beating a three-pet team. Perhaps someone else will find this helpful too.
By the way, can someone point me to a "beginners" guide for the quest to unlock the Pet Menagerie at level 100? I don't have a raft of rare level 25s to work with.