Very effective as a battle mount/travelling companion. I mostly play on single player so an effective companion is vital. I tamed my Kopiona when she was level 32...she's at 62 now with 200% melee damage, over 800 health and quite a few surprising kills notched into her tail.
Some noteworthy accomplishments (without my assistance) are:
-1 Carno killed (lvl 30)
-1 Spino (lvls 3)
-1 pack of 4 Raptors (lvls 36, 24, 18, and 50)
-Survived a Rex attack (lvl 24) after I had died with minimal health loss.
Coupled with its torpor inducing attacks, it's also great as a taming mount.
I tamed my eerie male scorpion on ark mobile during the eerie server event inside the poison cave. It was the best choice I ever made as he is now guarding my hatchery.
On mobile I recommend the following for stats if you plan to use a scorpion as a guard.
Speed is good at 230%
Melee at about 500% (just to keep those nasty wild Dinos spawning in your base in line)
Health about 5k (scorpions can be very easily killed if they don’t have good health in them.)