Various tufted tails! Scaly, fluffy, different colours and styles
Mainly fitting cats and then deer, bunnies, lions, easily all rodents, then eventually chickens..? like a basilisk, and horses - those two would need a thick base
They would easily work as Halloween items, unless a Summer event could match them up
These pets have some great tails, but the item tails could have really varied tips (not always fur) making them truly extraordinary
Edit: various matching ears would be also wonderful and make these into nice sets!
The tails could also fit dogs the same way the store lion/tiger outfits have it, to make it fit fully you'd have to cover the dog's tail with some other item