Pet Battle Progression

My recently concluded holiday travels provided a good opportunity to get back into WoW's newly added pet battle system.  Between its bite-sized gameplay and ability to run on less beefy systems, I was able to sneak in some pet battles between various family shindigs. 

In the process, I functionally completed the pre-Pandaria portion of the pet battle game.  My pet collection currently stands at 340 unique pets and counting, including all but three of the pets that can be captured prior to the new expansion content - the overwhelming majority of these are green or blue quality.  (The three stragglers are the Qiraji Guardling, which only spawns in summer, and two highly camped rare spawns, the Minfernal and the Scourged Whelpling.)  I have beaten all of the trainers up to the Cataclysm era (including the new Darkmoon Faire pet master) and leveled my first half dozen pets to the max level of 25. 

The real progression in the pet battle minigame is not just the highest level individual pet you can field, but also the overall diversity of your stable.  In general, wild pet battles will occasionally throw in something you weren't expecting, and the NPC pet masters are especially likely hit you with tough line-ups.  You can in principle tame and use whatever you find locally - indeed, a few of my pets are recent captures who started above level 20 - but you will likely need to catch and raise some pets to deal with high level pet battles. 

That said, there are a few downsides to the system:

• Because this system was added to the game in its fourth expansion, players looking to jump right into Pandaria will need to spend a fair amount of time catching up before they can actually battle the pets in the expansion content.  My approach - spending basically a month doing an extremely thorough world safari - is overkill, but the time is significant.  
• Account-wide progress is a blessing and a curse.  It is nice to be able to park alts in locations with rare spawns or account-level daily quests to re-battle the pet masters.  Perhaps I would have burned out on this system if I had felt that I needed to regrind it on any alts.  That said, short of creating a new account I will never have the option of starting over with a clean slate - any character I ever play will have all of these max level pets at their disposal.  
• Competition for rare spawns in the world can be somewhat unfortunate.  The two pets I just can't nab are constantly camped with multiple players at seemingly all hours of the day.  Because only a fraction of spawns are the coveted rare quality (there are items to upgrade pets later, but these are rare and expensive), pet completionists are not intended to stop at just one.  It's a bit jarring, because this level of competition does not occur anywhere else in WoW at the moment, so it's odd to see it rear its head in a minigame.  

Overall, I enjoyed my time in pet battles thus far, and look forward to being able to tame the new critters of Pandaria when I head over there.  That said, I don't know that the system will hold up in terms of longevity.  I can always level more pets and try to upgrade more greens to blues, but the benefits to doing so diminish as the power of my existing stable grows.  Blizzard is not done trying new things in this system just yet - a recent addition adds pet drops to some old raid content - but overall I don't expect pet battles to take up nearly so much of my time beyond the initial rush to catch everything in Pandaria.