Yes, Tyranitar is pretty hard to wall. Defensive teams do have better options, though;
252 Atk Tyranitar-Mega Power Trip (380 BP) vs. 252 HP / 252+ Def Unaware Audino-Mega: 225-266 (54.8 - 64.8%) -- guaranteed 2HKO after Leftovers recovery - even 2 shell smashes don't let ttar bypass it, and it can then easily haze, topsy, or spectral theif the boosts. Bulky fighting types like buzzwole can also wall, forcing out TTar with their stab while (with unaware/Fur coat) easily living a +4/4/4 power trip. Needless to say, it is quite dangerous, but it's not something as of now that Stall cannot answer, so don't rely on it exclusively to defeat bulky play styles.
Worth noting that simple Ttar generally packs sunsteel strike.
Anyway a noteworthy pokemon that I thought I should bring up is Mega Gyarados who has seen quite a bit of use as an unaware user seeing as it resists both sunsteel strike and moongeist beam.
248 / 232 / 28+ Bulk allows you to not get 2HKO by Owing from LO Modest Mega Ray (which is actually pretty rare) the rest being tossed in Physical bulk. This is what Ttar does to this after a Simple Shell Smash:
252+ Atk Tyranitar-Mega Power Trip (260 BP) vs. 248 HP / 232 Def Unaware Gyarados-Mega: 210-247 (53.4 - 62.8%)
+4 252+ Atk Tyranitar-Mega Sunsteel Strike vs. 248 HP / 232 Def Gyarados-Mega: 161-190 (40.9 - 48.3%)
Worth noting that I'm not bringing up a niche mon here like PhisDef Unaware Audino (that's just bad QT), Mega Gyara is actually a decently common Unaware wall.
Guess who else walls it?
252+ Atk Tyranitar-Mega Power Trip (260 BP) vs. 252 HP / 252+ Def Unaware Big-Zygarde: 349-412 (54.8 - 64.7%)
+4 252+ Atk Tyranitar-Mega Sunsteel Strike vs. 252 HP / 252+ Def Big-Zygarde: 269-317 (42.2 - 49.8%)
As for offensive teams, Simple Tar isn't immune to priority. And is weak to Triage Drain Punch (Mega Ray, Mega Heracross, MMX), Triage Leech Life (Mega Heracross, Mega Scizor), First Impression (Mega Scizor), Water Shuriken (Ash-Gren, Primal Kyogre), Bullet Punch (Kartana), Mach Punch (MMX), Aqua Jet (Water bub Mega Gyara) and Pixilate FakeSpeed (Mega Diancie, Xerneas). (I'd add Vacuum Wave but nobody uses that)
Prankster Haze also means you're getting rid of its White Herb which will make it considerably harder for Ttar to set up.