Darkrai Analysis [Incomplete]

Let us begin with the effects of the introduction of sixth generation for the Pitch-Black Pokémon:
- New type chart; Darkrai's STAB Dark-type attacks are now unresisted by Steel-type Pokémon. This is extremely beneficial for Darkrai since it can now hit Pokémon such as Genesect, Heatran, Scizor, Skarmory, Arceus-Steel, and Dialga with its powerful Dark-type STABs. But, the new type chart also introduces Fairy-type, which is super effective against Dark-type and which resists it as well. This is obviously unfavorable for Darkrai.
- Introduction of Arceus-Fairy, Xerneas, and Yveltal. All three of these Pokémon will defeat Darkrai as long as it avoids being put to sleep for some reason such as the activation of Sleep Clause or a miss.

First set:

Darkrai @ Life Orb
Ability: Bad Dreams
EVs: 4 Def / 252 SAtk / 252 Spd
Timid Nature
IVs: 0 Atk
- Dark Pulse
- Focus Blast
- Dark Void
- Thunder Wave

This set, in my opinion, is the most effective this generation for the following reasons:
- With Life Orb and the new type chart, very few in the Ubers metagame can switch into Dark Pulse, and even fewer can withstand two hits, which they may take thanks to Darkrai's superb speed.
- Focus Blast in conjunction with Dark Pulse give Darkrai great coverage. A hit of one Dark Pulse and one Focus Blast can KO Pokémon such as Excadrill, Ferrothorn, Heatran, Arceus-Normal, Arceus-Rock, Arceus-Steel, and Dialga.
- Thunder Wave is very useful for crippling several Pokémon on the switch after the opponent sleep-fodders another one of their Pokémon, such as Genesect and Terrakion, but Thunder Wave is extremely important for a greater reason; this reason is Xerneas. Without Thunder Wave, Darkrai would become complete setup bait for Xerneas, but with Thunder Wave, Darkrai is able to turn the tables, for a paralyzed Xerneas is a substantially less of a threat than a healthy one for sure.

Other Options:
- Darkrai can hold a Wide Lens to increase the accuracies of Dark Void and Focus Blast, which is much appreciated, since hitting or missing either of these two moves are often game deciding.
- Darkrai can hold a Focus Sash if you are confident in your hazard-controlling abilities, and can rise in utility as an emergency sweep-halter in situations where the opponent has setup a Swords Dance with Arceus-Normal or a Geomancy with Xerneas and you have lost your main counter to the threatening Pokémon.
- Darkrai can hold a Tanga Berry to ease prediction when dealing with Genesect, though this is situational since it is only useful when facing opponents using Genesect.
- Darkrai can learn Sludge Bomb over Focus Blast to heavily damage Arceus-Fairy, Arceus-Grass, and Xerneas, though it does not have much use outside of hitting these three Pokémon, while Focus Blast is generally more useful for it can hit Pokémon such as Tyranitar, Excadrill, Ferrothorn, Heatran, Arceus-Normal, Arceus-Rock, Arceus-Steel, and Dialga.

Checks and Counters:
- Blissey and Chansey have nothing to fear.
- Arceus-Fairy fears Thunder Wave only, while most variants don't mind being paralyzed too much.
- Choice Band Ho-Oh with Sleep Talk can switch in on a Dark Void and beat Darkrai about half of the time.
- Yveltal fears Thunder Wave only, while bulky variants don't mind being paralyzed too much.

Second set:

Darkrai @ Leftovers
Ability: Bad Dreams
EVs: 4 Def / 252 SAtk / 252 Spd
Timid Nature
IVs: 0 Atk
- Dark Pulse
- Dark Void
- Nasty Plot
- Substitute

This set should be used only if you have a sure counter to Xerneas such as Aegislash or Chansey. The great advantage this set has over the first set is the fact that it can beat Choice Band Ho-Oh with Sleep Talk. This is because in the case that Choice Band Ho-Oh switches in to take the Dark Void, two things can happen. First, you could hit the Dark Void, then Substitute until the Ho-Oh wakes up. Or, you could miss; in this case, you would Substitute. This puts your opponent at a checkmate because in the process of breaking your substitute, the opponent must give-up locking his or her Ho-Oh into Sleep Talk, meaning that putting the Ho-Oh to sleep the next turn would not be a problem.

Another plus about this set is the fact that it has a chance when dealing with Blissey or Chansey. Depending on the Blissey or Chansey's EV spread and move set in terms of whether or not it has Seismic Toss and Toxic, your ability to predict for whether to use Nasty Plot or to Substitute, and your luck, you may eventually defeat the Blissey or Chansey in a one vs. one situation.

The last characteristic of this set that makes it better than the first set is the fact that it has a better potential to setup and sweep thanks to both Nasty Plot and Substitute.

Other Options:
- Focus Blast can be used over either Nasty Plot or Substitute to better hit Pokémon such as Tyranitar, though the two moves in conjunction give you an overall better chance at sweeping the opponents team, such as in the case of Darkrai vs. Ho-Oh or Darkrai vs. Chansey.
- Darkrai can hold another item other than Leftovers, but this is not recommended since Leftovers allows Darkrai to setup more than four Substitutes as long as Darkrai is able to stay on the field for long enough for the recovery to take effect, which it often can thanks to Darkrai's offensive presence.

Checks and Counters:
- Again, Arceus-Fairy can live a Dark Pulse and OHKO back with a STAB Pixie Plate-boosted Judgment.
- Xerneas sets up without a worry.
- Yveltal defeats this Darkrai set as well in a one vs. one situation.