Possibly the most useful creature to go caving with as his small size but large health and damage allows him to withstand onycs,spiders and scorpions haven't encountered a arthurplura yet so not sure how effective he is against it
Ark's very own king Kong. You looking to cave dive, take this awesome tame with you. one or two should do, accompanied with a pack of dire wolf's, then your practically unstoppable. These tame has a knock back attack allowing you to throw in more hit than your nemesis and hey not to ignore their high damage and high hp, all this coupled with extra amor gotten from their helmet, They are basically waking bulwarks.
These guys SHOULD work similar to a companion in other games. It should be able to wield a sword along with the ability to wear more than just a helmet. Having a tame that acts as a warrior would be very cool for battle in ARK.