I still don’t understand why they haven’t already implemented a “cosmetic pet gnome” troop. They could’ve combined this rare “trans?”-gnome with the implementation of cosmetic pet gnome bait for purchase for just 9,99$. 
Surely would find some buyers. Normally such $ ideas don’t take long until they’re implemented. 
but I’d also second the opinion:
retire or finally effn overwork rewards: arena weekends
introduce: cosmetic pet gnome weekends
The short answer is “you’re not supposed to get them if you aren’t buying the Campaign Pass”.
My longer answer would be that those specific pests aren’t necessary for most kingdoms. You’ll probably require cosmetic pests of some sort at some point for a small number of kingdoms for which really high levels of progression are possible and for which you’ve satisfied all the other requirements. But for the most part, they’re an aid but not a requirement and the campaign pests are just one part of that greater “cosmetic pest” issue; there are many non-campaign cosmetic pests that have come from other things, whether Holidays (and other Observances such as GoW Anniversary) or with the seasonal events or what-have-you.
My supplement to that longer answer is that this appeared to be one of the aims/benefits to the whole “Legends Reborn” thing that seems to have abruptly wandered down the memory hole. That alongside the handful of new troops and the “re-balancing” of older ones, there was also the introduction of four troop-specific pests for that kingdom into the pool; that combined with a kingdom booster pest – now two with the advent of Starry Pests – and often a troop-type booster pest plus the delve pest was more than enough to fill all the requirements for kingdom progression.
As a guy who aspires to be more of a completionist because my OCD tendencies lead me in that direction, I’d like to see the return of an occasional Cosmetic Pest Saturday bringing back some of those pests, because I’m a proud VIP-0 player and the only campaign pests I own came from that avenue.
But I’m not holding my breath for that one and I don’t have any expectations in that direction.
If kingdom pass pets would only be obtainable via that campaign… Then same should apply for the tarots, mythical en weapons coming from it.
Also, players that now start playing will not have a chance to buy the pass as campaigns don’t return. It’s not making sense
Similarly they should not run pet rescues for past holiday pets either, but they do.
Update:
Buckee 0x
Bunnilope 0x
Kitterfly 0x
Lamplet 0x
Little Bang 0x
Love Panda 0x
Lovebird 0x
Minidusa 0x
Starlight 0x
Steam Kitty 0x
Sweetbuns 0x
Since my original post.
Including all kinds of pet offers.
Still on Xbox.
I would pay to get 1 copy of each pet …
I have seen little bang in one of the Harper’s menagerie offers on xbox
Do you already have a copy? Probably yes, otherwise it wouldn’t show up. 
I thought the whole point of Harper’s Menagerie was to sell pets people don’t own. Tries to sell me 31 copies via 3 different overpriced offers.
It’s only selling pets you already own but didn’t fully upgrade yet. At least for me and everyone I know. Some got those pets that I’m missing because they already have it in their collection.
iirc, the way it was introduced made it seem as though once you have a pet at level 20 it is removed from the pool, and the pool starts with ALL pets (minus some exclusives probably). So if you are missing 10 pets completely, but then own 50 that are not max level, you would be about 1 in 6 to be offered a pet you dont have. If this is the way it works, then getting as many pets to level 20 as possible SHOULD shrink the pool, making it more likely for a completely un-owned one to show up.
@Hayabusa I don’t own any copies of little bang and I have had other offers for cosmetic ones I don’t own
If it was working that way, I would be happy. Unfortunately it doesn’t seem so. 
I’m probably just unlucky then since this hasn’t happened to me ever.
well how many pets do you own that aren’t at level 20?
Not many. I passed 200+ at level 20 a while ago. Plus those 11 and the last few starry pets. Even though I would have to count how many of my pets are left at a lower level, statistically I should have encountered at least 1 of the missing pets over the years, either in an offer or a pet rescue.
well, this offer only started a small number of weeks ago, so you are looking for 11 pets, which you don’t own, and i’m going to guess you probably have at least 30-40 that aren’t max level, so if it works the way i believe it should, then you are only slightly unlucky to have not had the offer for a new pet yet. I currently have 112 pets at level 20, so it will likely be quite a while until i see a pet i don’t own already.
Additionally, do we know whether campaign cosmetic pets are even meant to be available through these new money offers?
Only 4 out of 11 pets that Hayabusa mentions were released through Wednesday rescue, remaining 7 are campaign items.
However, I can confirm that the system does indeed offer to buy cosmetic pets you own zero copies of.
Bumping this up …
Steam Kitty is a Steam exclusive Pet only available through purchasing the DLC on Steam.
It looks like all of these pets are cosmetic so only available through scheduled 24 hour Pet Rescue events and the Harper’s Magical Menagerie offer.
