Catburger is a Special Cat that was added since The Battle Cats 3.1. Beating the stage Minced Meet-Up, an exclusive stage for the English Version, will have a chance to unlock this unit. In the Japanese Version, no name or description of this unit can be found. (So maybe that's why he's English Exclusive?)
Normal Form: A simple burger with a Cat's face. The burger appears to have some cheese and lettuce. Yummy!
Evolved Form: Order up! This little burger becomes a monster meal! Piled high with 3 patties, lettuce, cheese, tomatoes, and condiments (most likely ketchup and mustard), the Cat Royale hops and flops around, and attacks by leaping and crushing the opponent. Looks like this is one burger that bites back!
Catburger is the exclusive unit for the English Version.
ID-182 is the exclusive unit for the Korean Version.
Baozi Cat is the exclusive unit for the taiwanese Version
Baozi Cat and Catburger (and their evolved forms) share the same stats.
In update 6.3 there is a bug where you can evolve him as is he were a catfruit evolution, although it requires no xp, no catfruit and level -1. It evolves into yet another Cat Royale, but it has the same stats as Cat Royale, has the appearance of Catburger and his icon in the upgrade screen and equip slot is the Mohawk Cat. How strange...