Don't get to excited!! You need 1 or 2 level 25 to do this quick enough.
Best spot I've found is in Vale of Eternal Blossom, vs Aquatic family.
Flying family skills increase damage by 50%. That's why I use my level 25 flying "Polly", which can be trapped in Northern Stranglethorn @ level 6-7. I also use an Amber Moth as backup, also rare level 25.
So, my team consist
Level (1-3) of any family (I prefer level 3, as they usally survive one hit)
Level 25 flying Polly
Level 25 flying Amber Moth (backup if Polly dies, but usally Polly solo 3-5 groups until it dies)
Engage a fight, just use one single skill with the low level pet and then change for a level 25. Stay on that pet even if it risk dying.
The experience is only split between all alive characters at end, that were active in the fight!!! If you're "lucky", you get a dot on your second level 25 pet, and if you're lucky with the "dot", killing your other level 25 meanwhile your target team last pet dies, then ALL experience will go for the low level pet. As much as ~1000 exp. for one fight.
It do not matter if you actually hit anything with your low level. All that matters is you used a skill, even if you missed, for one round. Then it's eligible for exp. at the end of the fight.
I've composed 2 videos. First one is leveling Lil' Teracgosa 3-10.
Second video is "uncut" leveling "Nuts" from 1-10 in rougly 17 minutes. I died at second fight as critters take 50% more damage from Aquatic damage.
I've leveled 10 to level 10 now, my next goal is to get Pristine Trap (15 to level 25). I will make video of the Pristine Trap when I got it.
I'm not Steven Spielberg so mind the quality of the editing.
This spot is usally where I level my pets to 25, it depends if they can handle these pets without taking extra damage due to their "family damage".
If anyone got a rare Spawn of Onyxia @ EU-Mekka (level do not matter!) then I'm willing to trade one of my level 25 rares with you.
I don't mind rare level 24 pet either, for "any" of my level 25's. Polly and my Amber Moth will stay with me, just because they are so nice to me!
Just contact me on Aggressiv @ EU-Mekka
Level 3-10 video (~3 minutes) http://www.youtube.com/watch?v=CyB3G3l9ABM
Level 1-10 video (~17 minutes) http://www.youtube.com/watch?v=X1I4vpo1p4U