Rainbow Unicorn
The Rainbow Unicorn is an EXCLUSIVE pet that could be hatched from the Exclusive Pets Egg, introduced in the Easter Update 2022. It had a 35% chance of hatching.
The latest Pet Simulator X value list for Rainbow Unicorn can be found below:

Regular
💎 7,300,000,000 (7.3b)

Golden
💎 Not Available

Rainbow
💎 Not Available

Dark Matter
💎 Not Available