"We’ve been receiving a few inquiries over Twitter and through email regarding Farmer Nishi, so we thought we’d share our thoughts on Pet Battle experience gains with you.This hotfix might not take full effect until next Tuesday's maintenance, but this is still great news. Pets no longer stealing other pet's experience will help make leveling a bit faster. No exploits or tricks needed. :)
We will soon be applying a hotfix that causes level-25 pets to no longer “steal” experience from your lower-level pets. Previously, if you had a level-3 and level-25 pet grouped together for a battle, the XP earned would be shared between the two at the end. This resulted in some players doing what they could to kill off their level-25 pet so the level-3 pet would get all of the experience. You no longer need to worry about this as the level-3 pet will now receive 100% of the XP that’s earned, so long as it has participated in at least one round of combat." - Crithto
With the Safari Hat combined with the increase of Pandaria Tamer daily experience gains, leveling should be a much quicker task.
Not only that, but leveling in the wild with max level pets should be more viable than before.
Currently max level pets are eating up some of the experience if they stay alive. Unlike a daily where it's this huge battle and a death isn't uncommon, wild pet battles shouldn't result in deaths, intended or not. But in order to grant your lower level companions full experience, you have to kill off those max level pets in a wild battle. This made leveling in the wild pretty inefficient.
With the experience gain change, we won't have to worry about this anymore. So I can hunt for stones AND level efficiently at the same time!