Moves
Knock Off is Mega Tyranitar's main STAB move, able to 2HKO almost anything that doesn't resist it when boosted by Choice Band and Tough Claws. Knock Off's side effect of removing items annoys Mega Tyranitar's switch-ins, and it particularly dissuades Eviolite Imposter Chansey and RegenVest Pokemon from coming in. Pursuit makes Mega Tyranitar into a fearsome trapper, punishing Pokemon like Giratina and Aegislash as they switch out trying to avoid Knock Off. Close Combat is a powerful coverage move that can OHKO bulky Dark-types like Mega Gyarados and opposing Mega Tyranitar and Steel-types like Registeel and Dialga. Close Combat also takes out Mega Tyranitar's Imposter with just a bit of prior damage or if it does not have Eviolite. Sunsteel Strike takes down Fairy-types like Xerneas and Mega Audino and also OHKOes Sturdy Shedinja. Alternatively, Ice Hammer can be used to OHKO Zygarde-C and Mega Rayquaza. Ice Hammer is also Mega Tyranitar's best option against Yveltal. With Adaptability, Diamond Storm can be used to take out Mega Rayquaza, Kyurem-B, and Yveltal and 2HKO miscellaneous Dark-resistant foes like Mega Gyarados and Mega Audino. First Impression and Sucker Punch are both decent options to surprise fast sweepers like Mega Mewtwo Y and Mega Gengar, especially in combination with Mold Breaker to ignore Dazzling and Queenly Majesty. Both of these moves are extremely poor to be Choice-locked into, however.
Set Details
An Adamant nature in combination with Choice Band makes Mega Tyranitar's Attack skyrocket, making it very difficult to wall with proper prediction. Tough Claws boosts Mega Tyranitar's contact moves, increasing its wallbreaking power substantially. It is typically the best ability on this set, as it powers up Mega Tyranitar coverage moves, enabling it to OHKO Registeel with Close Combat and Zygarde-C with Ice Hammer. Mold Breaker allows Mega Tyranitar to Pursuit trap Sturdy Shedinja and more easily break past Fur Coat walls at the expense of being weaker than Tough Claws in all other situations. Adaptability gives a significant boost to the power of Mega Tyranitar's STAB moves, but it does not boost its coverage moves as Tough Claws does. It should always be used alongside Diamond Storm, as this is its only notable advantage when compared to Tough Claws.
Usage Tips
Mega Tyranitar is best used as an early-game wallbreaker, breaking holes in defensive cores with its powerful attacks and Pursuit to pave the way for its teammates to sweep later in the game. Mega Tyranitar can Pursuit trap offensive Pokemon that it can take hits from, like Mega Rayquaza and Mega Gengar, and bulkier Pokemon that are weak to Dark, like Giratina, Aegislash, and Cresselia; however, while it is a very powerful tool, it is also situational and can be risky to become locked into. Be careful with it, as using Pursuit when the opponent doesn't switch can be disastrous for Mega Tyranitar. Furthermore, be mindful that Pursuit can give free setup opportunities to Pokemon like Poison Heal Regigigas. Mega Tyranitar does not often like to switch directly in against Pokemon like Giratina, as they can chip it and escape with U-turn or cripple it with a Will-O-Wisp or Knock Off as it switches in. Try to get Mega Tyranitar in safely against these Pokemon with a slow U-turn user like Mega Audino or RegenVest Primal Kyogre, on a double switch, or on a predicted move like Spectral Thief or Recover that won't hurt it. While Mega Tyranitar does make a solid check to Pokemon like Aerilate Mega Rayquaza and Mega Mewtwo Y, a lack of recovery makes this set fairly unreliable at switching into these Pokemon.
Team Options
Mega Tyranitar pairs well with Pokemon like Poison Heal Regigigas, Mega Mewtwo X and Mega Blaziken that appreciate its ability to Pursuit trap Pokemon like Aegislash, Giratina, and Cresselia. Choice Band Pheromosa is an especially good partner, as it can get Mega Tyranitar in freely through U-turn against the bulky Ghost-type Pokemon that it baits in. Between Knock Off and Close Combat, Mega Tyranitar is effective at weakening Imposter Chansey, so it partners well with Pokemon like Pixilate Mega Diancie and Mega Mewtwo Y that can struggle against Imposter. Slow Pokemon with U-turn like Registeel and Mega Audino can help Mega Tyranitar switch in freely. While Mega Tyranitar does a good job at dissuading Imposter Chansey from switching in, if it does get in safely, you should have a Pokemon to switch in against its Imposter. Depending on your choice of coverage move, bulky Fairy-types like Mega Audino and Xerneas or a Fur Coat Pokemon like Primal Kyogre can be a good candidate for this role.