The Siamese cat is a purchasable pet from Eeylops Owl Emporium & Magical Menagerie. It is bought at 11 Galleons. When bought, the Siamese cat becomes your avatar.
Description[]
"With its striking eyes, elegant frame and triangular pointed features, the Siamese cat is seen by some as the most attractive in the feline family."
Pottermore PlayStation Home[]
On Pottermore PlayStation Home, the Siamese Cat is one of the five cats available for purchase at the Magical Menagerie. It must be purchased with real money and costs £2.39.
When purchased, it will walk alongside the player's avatar in the game.