Giratina-O's titanic base 150 HP, in conjunction with its decent base 100 defenses, grant it enough bulk to switch into attacks repeatedly. Levitate makes this even easier, as it allows Giratina-O to avoid Toxic Spikes and Spikes and act as its team's Ground-type immunity. Offensively, Giratina-O can cause serious amounts of damage with its amazing base 120 offenses, access to very powerful STAB moves such as Draco Meteor and Outrage, and a priority move in Shadow Sneak. But Giratina-O's most powerful utility comes with its Ghost / Dragon typing, which grants it many resistances and immunities, gives STAB to powerful moves, and allows it to function as a spinblocker. However, Giratina-O is not without its flaws. It has weaknesses to common Ice-, Dragon-, Dark-, and Ghost-type attacks, and can only hold the Griseous Orb. Its average base 90 Speed also leaves it outsped by a large number of threats, and the lack of Choice Scarf leaves it with no way to reliably boost its Speed without resorting to the weak and gimmicky Bulldoze to decrease its opponent's Speed. However, the aforementioned traits are more than enough to make Giratina-O a monster offensively and defensively, and of course, one of the best spinblockers in the game.
Thanks to its STABs, high offensive stats, and the boost from Griseous Orb, Giratina-O is a deadly mixed attacker. It may not be as powerful as Dialga or Rayquaza, but its typing and bulk set it apart. Draco Meteor is Giratina-O's strongest attack and will leave huge dents on anything that does not resist it, bar Blissey and Eviolite Chansey. Shadow Sneak appears weak at first, but it allows Giratina-O to pick off weakened sweepers. Among the most notable are Mewtwo and Ghost Arceus, as they are both weak to it. Dragon Tail allows it to phaze enemies around to rack up damage with entry hazards and make setting up on Giratina-O extremely difficult. Combined with STAB, Giratina-O's naturally high Attack, and Griseous Orb boost, it will often leave a fair-sized dent in most Pokemon. The last slot allows Giratina-O to fulfill its spinblocking role effectively. Hidden Power Fire is specifically targeted at Forretress, but also grants it important coverage against Ferrothorn and Excadrill, provided that the weather is not rainy. However, its reliance on sunlight can be problematic. Giratina-O is more than capable of hurting Forretress even in rain, but Excadrill and Ferrothorn are able to swallow the attack without much of a problem. Should you find yourself running into more issues with Tentacruel and Excadrill, Earthquake is a solid replacement. It can also deal a sizable chunk to Tyranitar and Dialga. However, Giratina-O loses coverage against Ferrothorn and Forretress, allowing them to set up Spikes. If dealing immediate damage to Rapid Spinners isn't a concern, Will-O-Wisp can be used to generally cripple physically oriented Pokemon such as Swords Dance Ground Arceus and Tyranitar.
It is possible to run both Hidden Power and Earthquake to maximize coverage against the Rapid Spinners, but sacrificing one of the three other moves in the set can be tremendously crippling. As far as its Dragon STAB moves go, by dropping Draco Meteor Giratina-O loses a direct way of dealing quick damage and the ability to hurt Groudon, while forgoing Dragon Tail means that it can no longer truly abuse the entry hazards it spinblocks and leaves it open to being set up on. Forgetting Shadow Sneak deprives it of the ability to revenge kill Deoxys-A, Mewtwo (at 50%), and other weakened threats.Team Options & Additional Comments >>>
Although Giratina-O's Speed may not be appealing, Giratina-O can still attempt a sweep via Calm Mind due to its excellent bulk and reasonably powerful attacks. What makes this set dangerous is Giratina-O's Ghost / Dragon typing and access to Levitate, which grant it crucial immunities to Seismic Toss, Rapid Spin, Spikes, and Toxic Spikes. These traits allow it to set up Calm Mind with relative ease against stall teams and use Substitute to render Blissey or Chansey useless.
It's recommended to have Dragon Pulse as Giratina-O's main attack, due to its amazing neutral coverage; it also hits a myriad of Pokemon in Ubers super effectively. However, Shadow Ball allows Giratina-O to deal significant amounts of damage to Mewtwo, Mew, Wobbuffet, and most importantly, Lugia, who could otherwise wall it to an extent. Whichever move you choose, Aura Sphere complements the coverage, hitting Pokemon such as Steel Arceus, Heatran, Dialga, Ferrothorn, and Tyranitar for super effective damage. Thunder should only be used with Dragon Pulse for the best coverage. It hits Forretress, Kyogre, and Ho-Oh harder than any of its other moves and deals a decent amount to Lugia. However, rain support is needed to ensure that it never misses. Finally, you can use both of Giratina-O's STAB attacks to hit many Ubers super effectively, sacrificing general neutral coverage in the process. Be warned, however, that Ferrothorn can defeat Giratina-O without Aura Sphere.Team Options & Additional Comments >>>
With Rest and Sleep Talk, Giratina-O is bothered by neither Tentacruel's Scald burns nor Toxic from foes such as Blissey, Chansey, and Forretress; unlike the Substitute + Calm Mind set, this set can switch in more comfortably. Due to the huge boost in lifespan that Rest and Sleep Talk provide, this set makes an extremely efficient spinblocker, and because of Levitate, it outclasses Giratina, which is worn down by Spikes. This set is also extremely surprising; most people will think that it is the SubCM set and send in their defensive non-Ghost Arceus or Lugia, both of which cannot do anything but phaze. Power is also another huge advantage over Giratina. For example, at +1 Special Attack, Giratina-O will always 2HKO 252 HP / 200 SpD Dialga after Stealth Rock damage (while Dialga's Draco Meteor never OHKOes). Moreover, Giratina-O is not shut down by Trick, which is simply nullified; Giratina, on the other hand, is completely useless once Trick is used on it. This set is also capable of defeating mono-attacker Kyogre, winning the Calm Mind war due to its typing. This is something Calm Mind Arceus cannot accomplish.
Rest and Sleep Talk provide recovery and allow Giratina-O to absorb status, while Calm Mind transforms Giratina-O into a great attacker. Calm Mind also boosts its Special Defense, which rounds out it bulk and makes it quite hard to take down with both physical and special attacks. Dragon Pulse is a great STAB move to have, resisted only by Steel-types and hitting the vast amount of Dragon-type Pokemon in Ubers for super effective damage; it also gets a boost from Griseous Orb.Team Options & Additional Comments >>>
SpikeStacking is one of the most threatening and dangerous playstyles in Ubers, and this set is an amazing addition to this playstyle by being able to spinblock and shuffle. This set has a few advantages over Giratina, which is often considered one of the best spinblockers in the metagame. Firstly, Giratina-O is much more powerful than Giratina; Giratina-O's Dragon Tail will almost always break 208/0 Ho-Oh's Substitute, while Giratina struggles to do the same. Moreover, in contrast to Giratina, who is worn down easily by Spikes and Toxic Spikes, Giratina-O's Levitate ability allows it to hover over these entry hazards, avoiding the additional damage.
Giratina-O makes a wonderful stallbreaker due to its spinblocking capability, its Dragon-type STAB, and the combination of Rest and Sleep Talk. This is Giratina-O's only way to heal HP and cure status, which further allows it to fulfill its job as a spinblocker. The use of both Dragon Tail and Roar might seem like a waste of a moveslot, but if using Sleep Talk, Giratina-O has a 66.66% chance to phaze the opponent with either one. Roar is also capable of phazing Substitute users, whereas Dragon Tail can land a bit of damage.Team Options & Additional Comments >>>
Giratina-O is vulnerable to status. However, unlike the SubCM set, this Giratina-O makes use of Substitute and Dragon Tail to phaze and shuffle the opponent's Pokemon, all while behind the safety of its Rhydon doll. Like the mixed attacker set, this set can also check Mewtwo with Shadow Sneak. Earthquake hits the increasingly popular Mold Breaker Excadrill, whom you conveniently outspeed, Dialga, the odd Heatran, and Tentacruel, all for super effective damage.
Outrage can also be used in the last slot, as it is strongest attack Giratina-O can wield; Outrage is also the only attack that Ho-Oh fears. Will-O-Wisp is usable but recommended with a bulkier spread, such as 164 HP / 252 Def / 8 SDef / 84 Spe, with an Impish nature; it gives valuable chip damage against Skarmory, Ferrothorn, Forretress, and also cripples physical attackers like Groudon and Extreme Killer Arceus.
The Speed EVs give Giratina-O enough Speed to outpace 0 Speed Tentacruel before it can attempt to burn you with Scald. Attack is maximized to give Giratina-O's attacks some bite; for example, Dragon Tail OHKOes Palkia after Stealth Rock. The defensive EVs might seem strange, however, 172 HP EVs allow only three uses of Substitute, whilst 164 HP EVs lets Giratina-O use Substitute four times; the remaining EVs are split evenly between its two defensive stats.Team Options & Additional Comments >>>
Unlike the standard SubCM set, this set focuses more on Speed and catching your opponent off-guard. While initially this set seems outclassed by Ghost Arceus, using it allows you to use another Arceus forme and it flies over both Spikes and Toxic Spikes, allowing it to switch in more freely due to the popularity of Spikes in Ubers.
Dragon Pulse is a powerful STAB move further boosted by Griseous Orb and has good neutral coverage in Ubers. Thanks to Giratina-O's Dragon typing, Dragon Pulse allows it to OHKO most of the Dragon-types in the tier after just Stealth Rock damage, including Palkia, Kyurem-W, Rayquaza, and Zekrom, something standard Calm Mind Ghost Arceus can not accomplish. Aura Sphere is generally an awesome coverage move, smashing Ferrothorn, Darkrai, Tyranitar, Heatran, Arceus, and Dialga to pieces. Keep in mind that all of them are 2HKOed at best if you are unboosted. If you are worried about more obscure threats such as Jirachi and Heatran blocking your sweep, Earth Power can be used. It also hits Blaziken and Electric Arceus for super effective damage but Blaziken normally crumbles to Dragon Pulse anyway.
Thunder hits Ho-Oh, Skarmory, and Kyogre, all of which would wall Giratina-O otherwise. If you decide to go with Thunder, Kyogre's rain support is very useful for maximum accuracy. Shadow Ball decimates Mewtwo and Ghost Arceus while dealing more damage than Thunder to Lugia, but is generally inferior to Dragon Pulse as the main STAB. The main use of Shadow Ball is to destroy otherwise solid checks such as Ghost Arceus, Lugia, Jirachi, and Bronzong. Thunder Wave can catch something like Darkrai switching in and cripples many checks such as Arceus. Will-O-Wisp is better on other sets; Substitute could be used to block status, but this set relies on sheer power and surprise value, which Substitute does not provide. Due to the lack of Substitute, Blissey and Chansey will easily wall this set, so powerful physical attackers, such as Terrakion are great partners. This Giratina-O is somewhat fragile, so use it with hazards to ensure it KOes the things it needs to before they can take it out; Ferrothorn is a good partner, having perfect synergy with Giratina-O and setting up hazards.Team Options & Additional Comments >>>
Should Dragon Tail's negative priority and low Base Power not appeal to you on the mixed set, Dragon Claw or Outrage are viable options. If defensive Kyogre and Ho-Oh are problematic, Outrage is the superior option as it 3HKOes the former and 2HKOes the latter. It can also deal over 50% to all Arceus formes with 4 HP, barring Steel Arceus, and in conjunction with Toxic Spikes, Arceus will have a difficult time trying to stall it out. If none of those problems are of your concern, Dragon Claw is better as it lacks the locking drawback of Outrage, and thus can be thrown about much more easily. Keep in mind that in conjunction with entry hazards, Dragon Tail will do more damage on average than Dragon Claw and can potentially place the opponent in a bad position.
Stone Edge can be used to take down Ho-Oh but offers no real use outside of that. Giratina-O's signature move, Shadow Force, deals an incredible amount of damage, but its charge-up turn gives the opponent a free turn to possibly set up or put up a substitute, potentially leaving Giratina-O vulnerable to a powerful oncoming attack. Thunder Wave can cripple faster attackers such as Arceus and Choice Scarf Dialga. Destiny Bond is usable for surprise kills once in a while, but with Giratina-O's middling Speed, it is extremely unreliable and should not be used often. Magic Coat can be used to bounce back Spikes from Deoxys-S and Ferrothorn, as well as Dark Void from Darkrai, should you want to use Giratina-O as a lead. Giratina-O can also attempt to sweep from the physical side using Hone Claws, Shadow Sneak, Earthquake, and Dragon Claw, but its power in that department leaves a lot to be desired.
Checks and Counters
Lugia can generally wall whatever Giratina-O throws at it and whittle it down with Ice Beam or blow it away with Whirlwind, while setting up Reflect to weaken its physical moves significantly. The rare Cresselia also follows the same principle, minus Whirlwind. Steel and Dark Arceus, with their great bulk and Speed, can switch into almost anything that Giratina-O throws at it and heal off the damage with Recover. It can proceed to severely damage Giratina-O with Judgment. Heatran can counter mixed versions without Earthquake and Calm Mind versions without Aura Sphere. Tyranitar and Jirachi are also annoying for the Mixed Attacker set without Earthquake. Dialga can take a hit from Giratina-O and OHKO back with its own STAB Dragon-type attacks. Keep in mind, though, that Dragon Tail makes countering Giratina-O harder than it seems.
Giratina-O isn't too difficult to revenge kill due to its weaknesses, lack of item options, and average Speed. Choice Scarf Palkia, Dialga, Reshiram, and Zekrom can easily OHKO Giratina-O with their STAB Dragon-type attacks. Darkrai outruns Giratina-O, resists Shadow Sneak, and can severely cripple it with Dark Pulse or put it to sleep with Dark Void. Be wary of the Calm Mind set, as it won't be so easily taken down. However, it doesn't have as much initial power as the Mixed Attacker set and requires setup.