The Party Cat is an EXCLUSIVE pet that could be obtained from the free Anniversary Gift that was given to all Pet Sim X players above the Pro rank. The Anniversary Gift could hatch a Party Cat with an almost 100% chance. This pet was listed in the pet index of a previous update, but was not yet available until the Hardcore Anniversary Update in July 2022.
The latest Pet Simulator X value list for Party Cat can be found below:
💎 1,000,000,000 (1b)
💎 6,000,000,000 (6b)
💎 10,000,000,000 (10b)
💎 Not Available