Most of the time, Kaijus in Roblox Kaiju Universe are bought with G-Cells or unlocked with Robux.

All Roblox Kaiju Universe Codes As of right now, there are unfortunately no codes yet for Kaiju Universe in Roblox. Any codes that are created will come via Prometeo Games, the owner and developer ...

To get anywhere in Roblox Kaiju Universe, you need to continuously farm and collect G-Cells. After all, G-Cells are the main source of income in Kaiju Universe.