Zapdos is a great defensive check to several threats thanks to a few traits. The first is reliable recovery in the form of Roost, allowing it to stay healthy throughout the match, unlike many other Electric-types. The second is its solid bulk, which, coupled with a good defensive typing, allows Zapdos to check some of the tier's most dangerous threats, such as Aegislash, Mega Pinsir, and Scizor. Finally, Zapdos gets Defog, and is one of the best users of the move in OU. It can beat Bisharp, something no other Defogger can do except Mandibuzz, and is also useful outside of Defog. Unfortunately, Zapdos is held back by a Stealth Rock weakness and does not have the sheer bulk that some other defensive Pokemon possess. Furthermore, the Thundurus formes, both of which boast much more useful offensive abilities and Nasty Plot to help muscle through walls, outclass Zapdos offensively. When using Zapdos, be mindful of its limitations and play to its strengths and it will be very effective.
move 1: Thunderbolt
move 2: Roost
move 3: Defog
move 4: Heat Wave / Toxic / U-turn
evs: 252 HP / 168 Def / 68 SpA / 20 Spe
Thunderbolt is Zapdos's best STAB option, packing respectable power thanks to its base 125 Special Attack. Roost helps keep Zapdos alive and mitigates its weakness to Stealth Rock. Defog lets Zapdos keep any entry hazards off of the field. Heat Wave is the best option in the last spot to hit Steel-types like Scizor, Bisharp, and Ferrothorn very hard. Toxic can be used to wear down common switch-ins like Landorus-T, while U-turn can help Zapdos pivot on those predicted switches. Hidden Power Ice can be used for good coverage alongside Thunderbolt and hurt switch-ins such as Garchomp.
The EVs and Bold nature are designed to maximize Zapdos's physical bulk while still allowing it to outspeed maximum Speed Aegislash. Although Zapdos takes one more point of damage from Stealth Rock with 252 HP EVs, it also gets one extra point of Leftovers recovery, making up for it. The 68 Special Attack EVs guarantee the OHKO on Mega Pinsir with Thunderbolt, while the rest go into Defense to improve Zapdos's physical bulk. An alternate EV spread of 252 HP / 64 Def / 176 SpD / 16 Spe with a Calm nature is also good, allowing Zapdos to still counter Mega Pinsir while also taking on special threats like Thundurus and Landorus. Leftovers is the best item to improve longevity, but Rocky Helmet can also be used to punish physical attackers.
Try not to switch Zapdos into Stealth Rock too much without using Roost in between, as keeping it from being worn down by entry hazards is worth the loss of some momentum. When Stealth Rock is on the field, don't use Zapdos to handle things that will probably just U-turn out like Scizor; Zapdos will get worn down quickly if you do. Instead, save Zapdos for your opponent's sweepers that you can't handle otherwise, such as Mega Pinsir and Lucario. Try to keep Zapdos away from status because it hurts its longevity, especially Toxic. In general, try to keep Stealth Rock off the field as much as possible.
Physical Fighting-types are good teammates for Zapdos as they can scare away or set up on Tyranitar and Chansey, two Pokemon that like to switch in on Zapdos. Terrakion is a particularly good choice as Zapdos handles two of its strongest checks, Scizor and Aegislash, very well. Cleric support from the likes of Sylveon, Clefable, and Chansey is also nice to alleviate Zapdos's status woes. Wish support from them can also help Zapdos switch into Stealth Rock and powerful attacks without being forced to Roost, and Zapdos can take Steel- and Fighting-type attacks for them. In turn, they can switch into Pokemon such as Latios that beat Zapdos. Many Dragon-types such as Garchomp and Mega Charizard X can set up on Zapdos, so having a physically defensive Pokemon such as Hippowdon to handle them is very helpful.
Zapdos has several other options for sets. Substitute + Roost used to be a popular set on Zapdos, but it has trouble being very effective. Roar is a good move for shuffling the opponent's Pokemon and phazing out boosting sweepers. Volt Switch can be used, but Zapdos doesn't always want to switch and can get worn down that way. Discharge is another option, but it lacks the power of Thunderbolt. For example, it can't OHKO Mega Pinsir. Air Cutter can be used as a Flying-type STAB move. Zapdos also gets Agility and Baton Pass, but Scolipede does it better. Zapdos can go offensive with a set of Thunderbolt / Heat Wave / Hidden Power Ice / Roost, but Thundurus packs more of a punch. Finally, Zapdos gets Rain Dance, which can be used on a rain team along with its powerful Thunder.
Checks & Counters
**Stealth Rock**: Making sure Stealth Rock stays on the field is the easiest way to deal with Zapdos. Good Stealth Rock users include Terrakion, Tyranitar, and Landorus-T, since all of them can force Zapdos out.
**Special Walls**: Zapdos doesn't have the firepower to get past dedicated special walls such as Chansey and Mega Venusaur. Tyranitar and Hippowdon can handle Zapdos if it lacks Toxic, and the former even threatens it with a Rock-type STAB.
**Dragon-types**: Many of them, such as Dragonite, Kyurem-B, Mega Charizard X, and Latios can set up on or do major damage to Zapdos.
**Setup Sweepers**: If Zapdos doesn't have Toxic, it becomes setup bait for Terakion, Volcarona, Thundurus-T, and Calm Mind users.
**Boosted STAB Attacks**: Even fully invested, Zapdos doesn't have the bulk to take some of the metagame's stronger attacks such as Choice Specs Draco Meteors from Latios or Choice Band Talonflame's Flare Blitz.
**Rock- and Ice-types**: Pokemon such as Kyurem-B, Mamoswine, Terrakion, and Tyranitar can all take Zapdos out with relative ease.