The copycat is a cosmic entity that destroys other cosmic entities and then disguises as them. When it destroys a cosmic entity, the last entity it destroyed is revived. It also can decide to become it's true form again, which revives the cosmic entity it's disguised as.
It destroyed Bongus when The Cosmological Recycler was looking for Bongus and TCR found the copycat disguised AS Bongus and mistaked him as the real Bongus. The copycat knew what TCR was gonna do and quickly got out of the Bongus morph just in time.
It's true form is a white glowing sphere with black eyes and one is red that emits weird red circles that grow and fade overtime.