In terms of tactics, power, abilities, in all considerations these Kishin Eggs were replications of what they were in life. This was the power of Erika, as when they were alive she had recorded their data into her mind as an image, and had used that data to recreate them once they no longer existed in the same form as with that image she had recorded.

That said, they were still low-level Kishin Eggs. 

The one to attend to Neku's challenge was the gargantuan fleshmonger, Towering over him, the giant's arm had much more reach than Neku's own and so the giant was the first to punch, its massive appendage aiming for the entirety of the boy before him, and carrying a raw physical force that bordered on the absurd. This was an "earth-shattering blow" meant to utterly pulverize the target.