Zombies are a type of robot in Elmo’s Country 4. They are composed of Zombie Zoe and Oscar.
The first zombie robot was Zoe, who was reincarnated for an unknown reason. Her body was gradually deteriorating when she came back to life. Oscar was the second, and he teamed up with Zoe to defeat Elmo. However, they take control of Elmo 2, who builds them a body called Zoescar(aka Hybrid). They then dispose of their other bodies, and become Hybrid.
Zombies tend to behave the same as their non-damaged counterparts. However, over time, they get physically worse. An example is Zoe, who was once yellow, but turns very pale orange with moldy blackish-purple spots. The rot also affects their behavior, as Zoe literally staggers when she walks, and her voice glitches. Meanwhile, Oscar turns brown with multicolor blotches on his body, and both robots have fur coming off of them, exposing their metal skeletons. Once a zombie reaches a point where the body is too degraded, they must either abandon it and enter a new body, or remain inside the old one until they deactivate. A Muppet Bot must be deactivated twice to become a zombie, but can do more times.
Zombies can still be in normal mode for a few days, and they can even move properly.
Zoe apparently retains her original injuries, as her head slightly detaches from her neck when she jumps.
Oscar has been forced to drive a mechanical trashcan wheelchair, as the rot damages his legs.
Oscar has only been deactivated once, so he could be immune to the effects.
He might just be riding the wheelchair all the time, and not be crippled.
Zoe, however, has been deactivated twice: the first time was when Jack defeated her with a single blow, and the second is when her head is knocked off again.