Giratina

You can consider investing additional Speed EVs if you wish to engage in a Speed creep contest with opposing Groudon, Dialga, and Giratina. Other moveslot options include Toxic or Thunder Wave. Thunder Wave might have some use as a lure for fast attackers such as Darkrai, but Will-O-Wisp has more overall utility since this Giratina is supposed to counter physical threats. Finally, Shadow Claw can smack Mewtwo and Wobbuffet on the switch-in, but Darkrai and Dark Arceus still don't care. Bear in mind Shadow Claw is still pretty weak and will not OHKO Mewtwo even after Stealth Rock damage. It is nearly always better to phaze Mewtwo out with Dragon Tail instead of using Shadow Claw. Earthquake pairs well with Dragon Tail, and kills Heatran in one hit, when it would otherwise wall Giratina completely.

Giratina is countered by sweepers who can abuse its numerous common weaknesses. In particular, Darkrai, Dark Arceus, and Dialga will terrorize Giratina since it can't really hurt them. Powerful Dragon-types such as Rayquaza, Reshiram, Zekrom, and Palkia can easily 2HKO Giratina at worst with their incredibly powerful Dragon strikes provided they safely switched in on Giratina. However, all of the aforementioned Dragon-types hate to stomach a Dragon Tail or a potential Will-O-Wisp. In order to deal with these Pokemon, it's recommended to use partners such as Chansey, Blissey, Groudon, and Lugia. All in all, the best partner for Giratina is probably Forretress: the two have excellent type synergy, and Giratina protects the entry hazards set up by Forretress, while Forretress spins away the nasty Spikes which may hurt Giratina. Skarmory and Ferrothorn are decent partners to Giratina too. Both boast Dragon-, Dark- and Ghost-type resistances and can launch Spikes into the opposing battlefield which Giratina conveniently blocks. Ho-Oh is a decent partner because its special bulk and typing helps against the strong special attackers such as Dark Arceus and Palkia that plague Giratina. Lugia may share Ice-, Dark-, and Ghost-type weaknesses with Giratina, but checks most physical Dragon-types who plague Giratina while Giratina in return can absorb Thunder and Bolt Strike for Lugia. Groudon checks the physical sweepers Giratina cannot stop such as Rayquaza, Garchomp, Zekrom, Dialga, and Salamence thanks to its massive Defense stat and lack of Dragon-type weakness. Scizor gets a mention for sharing good typing synergy with Giratina and countering most Dark-types.

You can consider investing additional Speed EVs if you wish to engage in a speed creep contest with opposing Groudon, Dialga and Giratina. Other moveslot options include Toxic or Thunder Wave. Thunder Wave might have some use as a lure for fast attackers, but Will-O-Wisp has more overall utility. This Giratina is meant to abuse its resistances and squander resisted powerful Special hits such as Kyogre's Water Spout. However, even with this layout, Giratina still hates facing powerful Draco Meteors. Therefore, Blissey and Chansey are great teammates. The previously mentioned teammates, such as Forretress, Lugia, Groudon, Ferrothorn and Skarmory work for this set as well.

If you want to forgo Sleep Talk, Giratina has a number of options. Shadow Ball is useful against Mewtwo, while Will-O-Wisp is an option if you want this Giratina to act as a lure for Tyranitar, or as a check to physical Arceus variants and Groudon. Roar allows Giratina to boost alongside the opponent and Roar it out.

Unfortunately, none of these options let Giratina defeat its counters, which include many powerful attackers such as Darkrai, Dark Arceus, and Dialga. As such, partners to this set mirror that of the last two sets, meaning that Scizor, Blissey, and Chansey are good options. You may wish for Heal Bell support from Chansey and Blissey particularly because of the new sleep mechanics in this generation: the sleep counter resets upon leaving the field. Finally, you will probably want Toxic Spikes support from Forretress to help handle Chansey and Blissey, who give Giratina trouble otherwise. Ho-Oh also checks most Calm Mind Arceus and Darkrai for Giratina, while scaring off the pink blobs at the same time. Heatran is a decent partner for Giratina as it resists all of Giratina's weaknesses, while Giratina protects Heatran from Groudon and Earthquake Ho-Oh. Heatran can also check Dark, Ghost, and Steel Arceus, all whom can beat Giratina easily. Kyogre can be used to absorb Ice Beam and check most Calm Mind Arceus.

Weather doesn't really matter to Giratina, but Groudon is recommended as a check to the physical attackers Giratina cannot handle, such as Zekrom and Rayquaza. One of the Steel-type Spikers, Forretress, Ferrothorn, or Skarmory is a required partner for Giratina because of their type synergy and ability to lay entry hazards. Forretress is probably the best, since it also removes Spikes with Rapid Spin. Chansey, Blissey, Ho-Oh, and Kyogre all help check the special attackers that trouble Giratina. Kyogre's turbulent rain will make Reshiram sad while a powerful Surf can easily drown it. Chansey and Blissey can handle the special attacks which are too powerful for Giratina to handle such as a Choice Specs Dialga's Draco Meteor. The pink blobs can also wake Giratina up immediately after using Rest with Aromatherapy or Heal Bell. Kyogre can set up alongside most Calm Mind Arceus formes and eventually win the Calm Mind war with Surf or Scald, thanks to the weather and Kyogre's superior special stats.

If Giratina is used with Groudon and Forretress, you can use Ho-oh and Heatran, which are other excellent checks to Giratina's counters such as Dark, Steel and Ghost Arceus. Heatran can Taunt and eventually kill most special attacking Arceus formes, while Ho-Oh can bypass Calm Mind boosts with its incredibly powerful Sacred Fire or Brave Bird. Scizor can still work as a partner to counter Darkrai and Dark Arceus, with an added bonus of being able to revenge kill a weakened Rayquaza with Bullet Punch. Outside of that, however, Scizor is pretty much useless. Metagross is also a decent teammate for Giratina, thanks to its Steel typing and great Attack stat. Metagross can 2HKO most Arceus formes with its bone-shattering Choice Band Meteor Mash. Lugia can assist Giratina in walling physical or mixed attackers, such as Rayquaza and Garchomp. Steel Arceus resists most of Giratina's weakness and beats Dark Arceus one-on-one. Excadrill gets a mention for Rapid Spin and resistances to Dragon-, Ghost-, and Dark-type moves. The mole can also beat Dark and Steel Arceus one-on-one.

Shadow Ball can be used as the STAB attack to hit Mewtwo and Ghost Arceus harder, but its relatively low power and inability to take out Dragon-types is a letdown. Will-O-Wisp can be used in the last slot to cripple physical attackers, but as this set is attempting to sweep, it is a bit counter-intuitive. Earth Power is Giratina's best weapon against Jirachi and Metagross, who could potentially be annoying, and also grants it an easy OHKO on Heatran. Hidden Power Fire allows Giratina to OHKO Scizor and do more damage to Ferrothorn, but it is rather useless otherwise.

A Modest nature and maximum Special Attack investment allows Giratina to hit as hard as possible, while the rest of the EVs make it as bulky as possible. A more physically bulky spread of 112 HP / 252 Def / 144 SpA can be used to survive a Life Orb-boosted Outrage from Jolly Rayquaza at full health, although the power drop is very significant. Additionally, even if Giratina does survive such a hit, it's not going to be sweeping much anyway.

Strong, super effective physical attacks are the key to taking down Calm Mind Giratina. Life Orb- or Choice Band-boosted Outrage from Rayquaza, Zekrom, and Garchomp can OHKO Giratina, while Choice Band Crunch from Tyranitar and Icicle Crash from Mamoswine will also leave a huge dent. In addition, Bulk Up Dialga can defeat Giratina if it has some Speed investment and Outrage. Choice Band Metagross can be problematic as it resists Dragon Pulse and has enough bulk to tank Aura Sphere, and Giratina's lack of Will-O-Wisp allows Metagross to Meteor Mash it with impunity. Skarmory can force +1 Giratina out with Whirlwind if Giratina lacks Thunder; Jirachi can also be annoying with paralysis and Iron Head flinches.

For the reasons listed above, physically defensive Steel-types are excellent teammates for Giratina. Forretress can Rapid Spin away the Toxic Spikes that might force Giratina to Rest earlier than is desirable, while being able to set up Toxic Spikes of its own, which allows Giratina to defeat Blissey and Chansey more easily. Skarmory can also switch into Outrage and set up Spikes, but must watch out for Zekrom's Bolt Strike and Rayquaza's V-create. It is worth noting that these entry hazards are easily kept on the field by Giratina's spinblocking abilities. Magnezone can trap and KO Skarmory as well as Metagross locked into Meteor Mash. Groudon, especially Swords Dance variants, can take on Dialga, Tyranitar, Jirachi, and Metagross easily.

Giratina's other major enemies are specially defensive Calm Mind users. Steel Arceus resists Giratina's STABs while outspeeding to cushion Aura Sphere with its own Calm Mind; Dark Arceus and Ghost Arceus can do the same thing. Ho-Oh is therefore another great teammate for Giratina, as it can defeat most of the Calm Mind users that Giratina has trouble against. Darkrai is also an excellent offensive check to Ghost Arceus as it outspeeds and puts Ghost Arceus to sleep with Dark Void, and can then set up Nasty Plot to sweep.