Just a disclaimer: No, I'm not against Pet Battles. Despite this cynical and seemingly negative write-up, I still think this minigame is going to be enjoyable (for the most part) and will give many players an alternative to the basic PVE and PVP modes of gameplay.
However, I do feel compelled to point out some of the feature's shortcomings and possible downfalls. How can Blizzard address these potential issues? I'm not sure yet, but the sooner a discussion starts, the sooner the brainstorming can begin.
There are many issues that Blizzard is attempting to address, such as the quality value of certain pets, the trade/selling of companions, and the world PVP aspect. These are and should be priorities, since they affect nearly all participants of Pet Battles. However, there are the less acknowledged concerns that shouldn't be forgotten.
From a non-collector point of view, Pet Battles seems like it will be a fun minigame to pass some time. From a more completionist, collecting point of view, Pet Battles has the potential to bring more stress than fun.
First off, let's discuss the hard caps - 500 total unique pets, and up to 3 of the same pet.
Currently, there is a total of 503 unique pets, give or take a few that aren't available to most regions, plus the Yellow and Green Balloon which (last I checked) are still NOT true companion pets.
So the total number of unique pets is a problem from the get-go. Nevermind being able to have duplicates, how is even the most dedicated of collectors supposed to collect one of each pet when they can barely fit all of them into their journal?
This can easily be fixed, though, by raising or even lifting the cap. Either over time or just in general. Or more drastic action could be taken and some wild pets could be removed (specifically those that are essentially duplicate models but with different names).
Once we get past that though, being able to have duplicates might seem like a blessing, but is it? There are MANY wild pets that share the exact same model but have different skins. At face value, ok, being able to have 3 of the same pet will allow collectors to gather up all those pets of different colors, patterns, etc. right?
Sorry! At the last count, there are 249 wild pets. Granted, not all of them have many different color schemes, but a lot of them do. Even when rounded down generously, 150 wild pets x3 = 450 possible companions to capture. Add these to just the existing (not new) non-wild pets, and again, it's well over the allotted hard cap.
And this is only addressing the numbers. There's still the whole topic of being unable to collect the same pet of EVERY color (in some cases one unique pet model has more than 3 different color variations).
Setting aside the numbers and cosmetic aspect of Pet Battles, from a completionist's point of of view, leveling up 500 pets is going to be a nightmare.
After the initial novelty has worn off, the realization that you'll have to go from pet level 1 to 25 another X rounds for each pet team starts to set in. You won't have to start at the very beginning for every single pet, as you'll be collecting and capturing pets of varying levels while out in the world, but with a full list of companions in your journal, it's still a pretty daunting task to level up all of them to max.
Not only will it be a giant time and energy grind, it might start to get mind-numbingly repetitive as well. Let's face it, you can only hit one, two, and three so many times before your mind starts to travel elsewhere. The NPC dailies are a nice touch, but after fighting so-and-so for the Nth time, with the Nth pet team... well, it's enough to put off even the most determined collector/completionist.
I totally understand that Blizzard is going for longevity and repeatable gameplay, but without some tweaks and changes to how the minigame progresses to keep things engaging and interesting, it's going to be the same few actions over and over again. For most, this doesn't exactly fall under the category of "fun". More like "monotonous" and "tedious" after a while.
As I mentioned earlier, despite all of these unfavorable flaws, Pet Battles still has the potential to be a great minigame, and interesting pastime for all types of players, from collectors to completionists, to just those seeking a casual distraction from PVE or PVP.
Still, I think what I've mentioned are legitimate concerns, even if they might not take precedence and may only be issues for the minority in the community. My hope is that by pointing out some of the less discussed and acknowledged points, conversations can open up so that we may find a way to resolve or at least compromise so that everyone can get the most out of Pet Battles and continue to enjoy collecting these awesome little critters.