Tyranitar:
+Higher attack stat
+Gets even more special bulk thanks to sandstorm affecting rock types (as if its special defense wasn't good enough)
+Great movepool offensively
+One of the best users of dynamax thanks to weakness policy and its 7 weaknesses coupled with insane bulk while dynamaxed
-bad defensive typing (but that makes weakness policy even better)
-HP and defense is only slightly worse than hippowdon
But, it's in UU for some reason
Now, on to
Hippowdon
+Possesses a great offensive typing
+Slightly more physical bulk than t-tar
+Has reliable recovery, rocks, and whirlwind
-Awful special defense stat, plus it isn't even affected by sandstorms's sp.def boosts because its a ground type
-taunt fodder
-Its movefool is a shallow pit
But, its in OU
I personally do not see any reason to use Moto Moto over Tyranitar, and I dont see why they decided to ban it to UU either. So, why has Hippowdon been surging in usage while Tyranitar is being left in the dust?