The best way to defeat it is to play 100% legit, carry all your stuff and command all your Dino’s to the over seer, then eat narcoberrys or narcotics right in front of its face and you will beat it in no time, THIS IS EXTREMELY REWARDING AND WORTH THE TIME
Here’s what I don’t get, if the Overseer is what created and cares for the ark, then why would you want to kill it, because it’s whats allowed you to survive for so long.