Take a pair of 25's and a lowbie - I find 5 a safe level to start at - to a pet-rich area of 23-35s. Southern Kun Lai is great I think, nearly all beast/critter types. Do the 1 round swap with the lowbie and burn through them with your 25s.
This is what I was trying out last night. Southern Kun Lai, in particular. Seemed like a really good zone for lots of pets to battle without moving around a lot. And, go go Clockwork Gnome :-). I was mainly focused on trying to get the level 10 achieves for each type and 15 to level 10, so I didn't push the lowbies to 25. But, the technique worked great. I'll come back when I start pushing for the level 25 stuff.
I do need to get the tamers done, but I'm thinking I want more diversity in my high level pets to do the higher level tamers. So, for now I'm postponing it.