The fact that it is a Ghost-type Uber with an insane physical walling ability makes Giratina a staple on Uber stall teams. Due to Giratina's Ghost typing, it blocks Rapid Spin; meaning Toxic Spikes, Spikes and Stealth Rock will not be removed easily. Giratina's immunity to Explosion means that it cannot be swiftly brought down. While its weaknesses are commonly used attacking types in the Uber metagame, one should not overlook its two immunities and six resistances. Giratina's massive defenses on both sides make it difficult to KO (even a Modest Kyogre's Ice Beam fails to 2HKO a Giratina with no SpD EVs). On the physical side, there are no unboosted physical attacks that will OHKO Giratina. In fact, Giratina's Defense is so high that it is possible for it to survive an Outrage from an Adamant Choice Band Rayquaza. Giratina is often noted as one of the few counters to the "Extreme Killer" Arceus.
However, Giratina does lack a reliable recovery move. For a winged lizard, it shamefully does not get Roost. However, it does not truly need such a move, as Rest, Sleep Talk, and colossal defenses are enough to make up for that loss.
Giratina is arguably one of the best physical walls in the game. With colossal base 150 HP and massive base 120 Defense, Giratina can easily wall some of the most dangerous threats in Ubers, such as Groudon, Metagross, Scizor, and Ho-Oh, with little effort.
Will-O-Wisp cuts Giratina's enemies' Attack stats to pieces, rendering them incapable of hurting this great wall, as well as biding time for Giratina to use Rest to restore all of its HP, thus becoming ready to take on the next opponent it faces. Sleep Talk enables Giratina to absorb status and ensures that it isn't set up bait for Rayquaza and Arceus, seeing as Sleep Talk may pick Will-O-Wisp and ruin their fun. Roar also allows Giratina to act as a good phazer and can be used over Will-O-Wisp if your team relies heavily on Toxic Spikes, because then Giratina could not burn as many opponents. Giratina also has a distinction as the only common spinblocker, aside from its counterpart Giratina-O, that can phaze. Dragon Claw enables Giratina to severely damage other Dragon-types, OHKO Deoxys-A, and deal a respectable amount of damage to Ho-Oh and Darkrai; whereas Dragon Pulse carries a dash more power against Groudon. Outrage will do more damage than Dragon Claw, and Giratina will not be locked in to Outrage if it is selected via Sleep Talk. However, use it sparingly when awake, as Giratina will then be vulnerable to being revenge killed.Team Options & Additional Comments >>>
Giratina can also utilize Calm Mind in order to boost its stats on the special side without having many problems with taking physical assaults, thanks to its high Defense. To keep Giratina alive, it must Rest so it can continue to set up more Calm Minds and eventually unleash a powerful Dragon Pulse. To further aid its set-up, it can use Sleep Talk to use moves while it sleeps. It is the preferred option so Giratina does not become set-up bait for opposing sweepers. It can then use its sleeping turns to further stat up or dent your opponent with Dragon Pulse. Will-O-Wisp lowers the opponent's Attack, allowing it to take hits on the physical side with greater ease. Roar keeps opposing Calm Mind users from setting up on Giratina. Shadow Ball lets it hit Psychic-type Ubers such as Mewtwo and Deoxys-D while still doing a decent amount of damage to Metagross. You must be aware, however, that most of Giratina's weaknesses lay on the special side, which may hamper its ability to set up, unless it already has a few Calm Minds under its belt.Team Options & Additional Comments >>>
Although Giratina is usually seen as a nearly impenetrable physical wall or sturdy Calm Mind booster, this set allows it to effectiely fill the role of an attacking lead. The combination of powerful attacks, strong priority, and Haban Berry makes Giratina one of the most reliable ways to defeat common leads such as Deoxys-S, Deoxys-A, Groudon, Mew, Rayquaza, Giratina-O, and Tyranitar.
Draco Meteor followed by Shadow Sneak is a guaranteed KO on 252 HP / 4 Def Deoxys-S, limiting it to a maximum of one layer of entry hazards. Deoxys-A is defeated by the same combination of attacks, while Groudon and Mew will struggle to do any meaningful damage as Giratina hacks away at their health with its attacks. Will-O-Wisp is useful for burning Groudon, but Hidden Power Fire is also an option to defeat Forretress and Scizor provided that rain isn't present. Unlike Giratina-O, this Giratina also has the ability to defeat Rayquaza, and by extention, Giratina-O leads, thanks to Haban Berry. Finally, Aura Sphere 2HKOes 252 HP / 0 SpD Tyranitar, and gives Giratina a reliable way of damaging Dialga and Heatran.Team Options & Additional Comments >>>
The best EVs to use for Giratina are listed in every set. Dumping the EVs into Special Defense instead of Defense is an option. However, since Giratina's weaknesses are more often special than physical, it isn't recommended. 24 EVs in Speed allows Giratina to outrun a max Speed Tyranitar and no Speed Groudon and Dialga.
Giratina has a lot of other attacks it can use, but there is not much that is actually more useful than what is mentioned above. Toxic and Roar are usable options on the Rest/Talking set, but that means you can't touch Steel-types. Losing Will-O-Wisp means you lose part of Giratina's ability to wall things physically. Of course, one cannot forget its signature move, Shadow Force. While it does have base 120 power, it is incapable of hitting Normal-types such as Blissey and Arceus, who may attempt to switch in on the charging turn. In addition, Steel-types like Skarmory and Forretress can take it without much trouble.
One should not underestimate Giratina's offensive capabilities. It has a large offensive movepool and two of the best STAB in Ubers, so it can make use of a Choice Band or a Choice Specs set to hit hard and surprise its counters. However, Giratina is rather slow. While Base 100 offenses aren't bad, they are slightly below average for Uber play. Furthermore, its cousin, Giratina-O, generally outclasses Giratina in the way of offense.
Checks and Counters
For the standard Great Wall set, Dark-type Arceus will easily Calm Mind and launch a super effective Judgment against Giratina. The same applies for Ghost- and Ice-type Arceus. Dragon-type Arceus can do the same too, but Dragon Claw will dent it. Blissey can Calm Mind and eventually beat Giratina with Ice Beam. Dialga can switch into anything Giratina throws at it and OHKO with Draco Meteor (most variants also 2HKO with Dragon Pulse) or Bulk Up and eventually defeat it with Outrage. Dialga can also use Rest to remove burn. Darkrai can come in on Rest, Taunt Giratina, and then Calm Mind or Nasty Plot and wipe Giratina off the battleground with Dark Pulse. With Giratina self-resting to remove the damages dealt to it, Darkrai is now able to put another member to sleep with Dark Void, since Sleep Clause is not active. Mewtwo is capable of doing the same, minus the Dark Void. Mew can Taunt Giratina and then Nasty Plot and Baton Pass away to a dangerous recipient, such as Palkia or Arceus.
The Calm Mind set is harder to counter. Your best bet is a Dark-type Arceus with Substitute to laugh at any status attack it throws at you, but beware of Roar. Latios and Latias can easily Calm Mind alongside Giratina, Recovering any Dragon Pulse damage it throws at any of them. They must, however, be aware of Toxic or Roar if they decide to Calm Mind alongside Giratina. While Giratina Rests, physical attackers, such as Ghost-type Arceus, are able to take advantage of the situation and set up, following up with a dangerous Shadow Claw. Tyranitar has a safe switch in on Calm Mind, Dragon Pulse or Rest due to the Special Defense boost from sandstorm, but must be wary of Toxic and Will-O-Wisp. If those are absent, Tyranitar can easily inflict serious injury with Crunch.