Sizes can not be bred for so are not considered a "trait" or are refered to as a bonus trait. Collars are just something you can add to a kitteh by buying them at the main store or one of the many talented creators who have made some with the collar kits. They can also wear hats or glasses and t-shirts.
So the most traits you can breed for its 9 traits. Hope this helps
KittyCatS lover and LazyCats auctioneer. 
