Why isn't shangtsung

So guys like why isn't Shang tsung the most powerful ? I mean he can transform into anyone and knows all their moves. So i just don't get from an outside appearance how he isn't at the top of the food chain in mortal combat.

@shonen3: Maybe it's similar to how Taskmaster is. He can copy the moves that Spider-Man does but he'll never be able to perform them with the same agility or flexibility.

Because Shou Khan is a thing.

He mostly relies on dirty underhanded tricks to win. I don't think he can sustain combat transformations for very long