Tyranitar is instictively ruthless, being able to change the landscape on a moment's notice. Its thick armor apparently protects it from all attacks, including dynamite explosions and bladed objects. Naturally, many Tyranitar are extremely eager for a challenge, pitting itself against threatening foes such as Hydreigon and Metagross, often coming out victorious due its brute force. However, it does lack mobility, and can often be dodged about by faster opponents, frustrating it.
Based on Tyranitar's reptile-like appearance and sharp teeth, it is possible that Tyranitar is a carnevor.
Tyranitar's thick armor provides it with a defensive ability beyond many others. With this defense comes great Physical offense as well. Stone Edge, Crunch, and Earthquake are all moves that Tyranitar uses to its full potential.
Rock Slide hits hard, hits many a Pokemon, and hits reliably. It's TTar's most dependable STAB, and it is very threatening. The flinch doesn't matter, though. Tyranitar wouldn't outrun many Pokemon anyway. Earthquake has perfect coverage with Rock Slide, and is learned naturally. However, Dynamicpunch, although unreliable, hits bulky switch-ins such as Miltank and Umbreon with unbelievable power. Pursuit works extraordinarily well, as you can catch Alakazam and Gengar in a switch. Crunch only takes other bulky Pokemon who want to stay in for any reason like Misdreavus and... Hypno? Pursuit is the better choice, but if you're terrible at predicting, go with Crunch. Fire Blast takes Physically defensive Steel-types (which is pretty much everyone), but especially Forretress and Skarmory.
Bulky Defensive (OU)
252 HP / 252 Atk / 4 Def
Earthquake / Roar / Dynamicpunch
This set revolves around Tyranitar's great defenses as well as its amazing Attack. Boost up with Curse as much as possible. Rock Slide is Tyranitar's STAB, while Earthquake hits what Rock Slide can't. However, Roar gets rid of many Pokemon to threaten TTar, but Dynamicpunch demolishes Umbreon and Snorlax. Finally Rest keeps TTar healthy while it sets up and deals damage.
Dragon Dance Sweeper (OU)
Adamant (+Atk, -SpA) or Jolly (+Spe, -SpA)
4 HP / 252 Atk / 252 Spe
Brick Break / Taunt / Substitute
Dragon Dance is an extremely useful move, especially on slow Pokemon. Tyranitar is possibly the best user because it receives STAB from a Physically attacking move, as well as being gifted with truly amazing defenses. With Speed, Attack, Defense, and Special Defense all extremely high, Tyranitar can sweep uninterrupted. Rock Slide and Earthquake have perfect coverage, and are both boosted by Dragon Dance. Brick Break hits Snorlax and Miltank hard, but Taunt prevents pHazing from Skarmory and Weezing. However, Substitute not only protects you from status and damage to an extent, but it often results in making the opponent think that you are running the set below.
Wall Breaker (TyranBoah) (OU)
Quiet (+SpA, -Spe)
252 HP / 188 SpA / 68 Spe
Thunderbolt / Flamethrower
Ice Beam / Crunch
As Serebii called it, "the Anti-Metagame Pokemon." This set completely neutralizes annoying walls like Blissey, Skarmory, and Regice both by hitting their weak spots and outspeeding them. The reason why this set works so well is because the Substitutes that are created, assuming you have perfect IVs in HP with 252 HP EVs invested, will have 101 HP each. This means that a level 100 Blissey can't break the Substitute in one Seismic Toss. This may seem trivial, but when you realize how many walls use moves like Seismic Toss, 101 subs become a blessing.
Focus Punch deals with the aforesaid Blissey and Regice, but also deals with fat Pokes like Snorlax and Miltank relatively well. Thunderbolt takes Skarmory out in two hits, as well as dealing with many bulky waters such as Vaporeon, Milotic, and Suicune, but Fire Blast deals with... Skarmory again, but also Forretress and actual attackers like Heracross and Breloom. Ice Beam disposes of many Dragons while Crunch takes Gengar and Dusclops.
Breaking walls are the key here, not sweeping. This set clears the path for other sweepers to attack.
Special Attacking (OU)
Modest (+SpA, -Atk)
Choice Specs / Leftovers
252 HP / 252 SpA / 4 Spe
Hidden Power Grass / Thunderbolt
Flamethrower / Fire Blast
This set also involves breaking walls, but it traps frail Ghosts and Psychics like Gengar and Alakazam, with the former being the most important thing to take out. Spikes can ruin your day, especially if you are switch happy, so spinblocking will ruin your day even more. Pursuit takes care of this. With Choice Specs, this will be a guaranteed kill. The rest of the moveslots focus on taking certain threats, so pick which one takes care of the biggest annoyances to your team.
Hidden Power Grass, although difficult to get in-game, takes care of Swampert, a popular defensive choice. However, Thunderbolt smashes bulky waters that aren't named Swampert harder. Flamethrower and Fire Blast eliminate Forretress and Skarmory, so it's accuracy vs. power, since they hit the same thing. Finally, Ice Beam demolishes Dragons.
More Dragon Dancing, except with better STABs, better moves in general, and items. Life Orb boosted +1Stone Edge is something not many Pokemon are willing to take, running at the base power of 293. However, Crunch also provides reliable STAB thanks to the Physical/Special split, allowing it to hit new threats like Dusknoir. Earthquake is a given, as it has perfect coverage with Stone Edge even in Generation IV, hitting Steels extremely hard. Taunt removes the fear of being pHazed and losing your stats, but Fire Blast takes the most prominent pHazer, Skarmory, anyways. However, if you are boosted by +2 or +3, then Fire Punch ought to do that accursed armored bird in just as well.
Choice Band (OU)
Adamant (+Atk, -SpA)
4 HP / 252 Atk / 252 Spe
Stone Edge / Crunch
Focus Punch / Ice Punch / Fire Punch
Choice Band Tyranitar is not something to scoff at. It will destroy your team if you are unprepared. Stone Edge and Crunch are both reliable STABs that you can safely lock yourself into. Earthquake deals with threats. Now we come to the real power that is Pursuit, or physical Pursuit, I should say. Again, the Physical/Special split has been very, very handy for Tyranitar here, as well as many trappers who love to spam Pursuit. If you switch into a Bliseey and they try to run, Pursuit will shave off a clean 55.8 - 65.9% before she can even say anything. Focus Punch requires careful prediction, but when used right, you may be able to destroy any incoming counters. Ice Punch deals with Gliscor and dragons easily and requires less prediction, but Fire Punch removes Forretress and Skarmory from the field so quickly, it's not even funny.
The only problem with this set is that it can be played around by experienced players as this is a very famous set. The second they know you're choiced, they will exploit this. Use this set with caution.