Skeleton is a Halloween limited pet, no longer obtainable as of Update 10 on 11/9/2018. It has a rarity of 2 and a half stars, with 150 as its Coin Collection and 100 as its Agility.
Not to be confused with Skeleton Ghost.
When golden, the Skeleton's stats are multiplied to 450 Coin Collection and 300 Agility.
When rainbow, the Skeleton's stats are multiplied to 750 Coin Collection and 500 Agility.