It probably and most likely is based off of BlackGlasses for the reason you said, its a Dark Type. It is not however the item BlackGlasses as Krookodile has red outlining and the item does not. We can assume it functions like the BlackGlasses, because we've seen Krokorok stop battling because it has lost its glasses, though for the reason that it has a strong personal attachment and not because it weakens it. Maybe it becomes upset and discontinues to perform because it is upset that it is weaker? All I know it is not the item, but is more than likely based off of it.