I only know of a few that ended up like that: Dragons / White Wyrms bcuz after the patch they are supposed to be 3 slot but have dramatically reduced str like 350-450str (The Prepatch ones have 750ish str) / Nightmares prepatch are 2 slot pets and after the patch got moved to 3 slot with a small chance for really bad ones to be 2 slot. / Hellhounds should have gotten buffed base stats like 150-300hp and str 125ishdex and I honestly dont know about their intelligence but because of the buffs they moved them to be 2 slot where prepatch ones are lower stats but 1 slot. The same thing for hellcats.
Although the following creatures in my mind deserve to have reduced slots as they can go to 5 slots but have TERRIBLE stats and HP which make them literally worthless (I know this is less important than the bug fixes but I figure that I might mention it while you are inside the guts of the coding):
The skree starts at either 3 or 4 slots. I think prepatch ones are 3? They have awful stats and cannot be made a viable pet at all. I think they deserve to be a 2 slot pet.
Dread Spider has this same issue they are a 3 pet with the same problem as the skree...with stats so low they cannot be made useful in anyway and they have necromancy which is an option that very very few pets have most of which share this same problem. (IE: Shadow Wyrm / Dread Spider/ Tsuki Wolf ). I think they deserve to be a 2 slot pet - 3 slots is FAAAR too high for a pet with the stats of a 1 slot hellhound.
Tsuki Wolf is on the edge of being totally underpowered. You can build one but they suffer from the necromancy curse of being useless. I think they deserve to be a 2 slot pet.
3 slot horses the buffed nightmares are just so much worse in comparison to the cu sidhe which already have healing and better stats. The only advantage the horses have is that is possible for them to train in necromancy. Prepatch mares are roughly equal to cu sidhe but after the patch going f rom 2 slot to 3 slot makes them not useful imo. I think they deserve to be left a 2 slot pet.
4 slot Rune Beetles do not have enough points in comparison to ANY of the other beetles and this makes them not viable. You can make a giant beetle that is better than a rune beetle in every single way. I think they deserve to be returned to a 3 slot pet.
Bake Kitsune after the patch was bumped to a 3 slot pet when they already werent really used much as a 2 slot pet. This makes them only have 2 rounds with low hp / resists / str. I think they deserve to stay a 2 slot pet.
Ki-rin: The are like a worse same slot version as unicorn. In my mind they should go from 1-5slot. This would make them more versatile than the unicorn since unicorns are totally immune to poison. I think they deserve to be a 1 slot pet.
Shadow Wyrm: This critter would be a very viable choice with a single round of training from 4 slot to 5 slot. They have a lot to offer but none of their skills are above 100 and since they dont get to train they are left with bad resists and low skills which leaves them totally underpowered. They are in no way stronger than any of their dragon brothers (Greater Dragon / Frost Dragon) I think they deserve to be a 4 slot pet.
Dragon Wolf: Are supposed to be a melee damage bruiser of a pet but they are held back because due to their high strength they cannot put points into dex and start with it very low like 50 dex which means they move at a glacial pace. Coupled with the fact they start at 4 with nothing special outside of 800str+ they are lackluster in everyway. They look so cool, I would love to see them go to 3 slot like an old dragon.
