kinda barebones, i did this in like 5 minutes so we would have something for the dex. any lacking info would probably be in the team options, so tell me if i'm missing stuff
Overview
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Boasting high Speed, good Special Attack, and a key Electric typing, Raikou finds a niche in XY OU as a check to top-tier threats such as Thundurus, Talonflame, and Mega Pinsir. With the aid of an Assault Vest, it can check even the likes of Greninja and pivot about with Volt Switch, functioning as a nice glue Pokemon for offensive teams weak to these specific threats. Not only that, but it can function as a devastating Calm Mind sweeper against unprepared teams and has decent coverage that makes it far from one-dimensional. Poor physical bulk, generally unimpressive power without a boost, and being easily handled by special walls hold it back significantly, but Raikou still manages to shine in a tier dominated by powerful Flying-(add dash) and Electric-types.
Assault Vest
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name: Assault Vest
move 1: Thunderbolt
move 2: Volt Switch
move 3: Hidden Power Ice
move 4: Shadow Ball / Extrasensory
item: Assault Vest
evs: 252 SpA / 32 SpD / 224 Spe
nature: Timid
Moves
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Thunderbolt is Raikou's most reliable STAB move; it has great the most damage (Even though it isn't viable, Thunder is stronger, just say "great damage output") output and poses a great threat to Water-types and Mega Charizard Y, (RC) which Raikou is generally supposed to check. Volt Switch gives it a safe move to pivot around with and wear down defensive threats with, especially in conjunction with entry hazards. Hidden Power Ice is compulsory coverage to hit Landorus, Landorus-T, Gliscor, and Garchomp, whoich otherwise completely wall Raikou. In the last slot, Shadow Ball 2HKOes Latios on the switch, while Extrasensory threatens Mega Venusaur The last slot boils down to whether 2HKOing Latios (Shadow Ball) or actually threatening Mega Venusaur (Extrasensory) is preferred.
Set Details
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The EVs provide enough Speed to outrun Thundurus and the firepower needed to threaten its opponent for Raikou to have a good enough damage output, with the rest in Special Defense to get a bit more special bulk out of the Assault Vest. Max Speed can be run to Speed tie with Starmie, but it isn't common enough to be worth sacrificing bulk that comes in handy against threats such as Greninja.
Usage Tips
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Be wary of switching in and out a lot with this Assault Vest Raikou, as it will be worn down quickly. When in doubt, uUnless the opponent has a bulky Ground-type waiting in the wings to switch in, using Volt Switching out is usually the best option unless you absolutely have to stay in and attack. This keeps the momentum of the battle in your favor. If the opponent has a bulky Ground-type on their team to switch in, just hard switch out anticipating the play.
Team Options
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Pokemon such as Skarmory and Mandibuzz that can handle Ground-types and physical attackers in general are useful make great teammates. Entry hazards limit this Assault Vest Raikou's longevity immensely due to its lack of Leftovers, so Defog or Rapid Spin support is greatly heavily appreciated. It fits well into VoltTurn cores with Pokemon such as Scizor and Landorus-T.
Calm Mind
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name: Calm Mind
move 1: Calm Mind
move 2: Thunderbolt
move 3: Hidden Power Ice
move 4: Extrasensory / Substitute
item: Leftovers
evs: 32 HP / 252 SpA / 224 Spe
nature: Timid
Moves
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Calm Mind boosts Raikou's Special Attack, allowing it to function as an effective boosting sweeper. Thunderbolt is the main STAB attack, providing the most power needed against neutral targets. Hidden Power Ice covers most Ground- and Dragon-types, whoich would otherwise wall Raikou. Extrasensory gives important coversage on important targets such as Mega Venusaur, as well as Assault Vest Conkeldurr. If Raikou's teammates can handle Mega Venusaur adequately, then Substitute is an option to protect it from status and revenge kills. Volt Switch is another option, allowing Raikou to pivot around and have general use throughout the match; however, it is prone to being worn down and thus might have trouble sweeping, and it becomes hard to justify this over an Assault Vest variant.
Set Details
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The Special Attack and Speed EVs enable Raikou to outrun Thundurus whilst hitting as hard as possible. The rest is dumped into HP for a tad extra bulk. Leftovers is a necessity to keep Raikou healthy so it can survive to set up and complete a sweep.
Usage Tips
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This Raikou can set up on Thundurus and Aegislash, two of the largest threats in OU, making setup often not difficult. Naturally, don't set up until Raikou's counters have been removed; until it can sweep, switching in at all should be avoided at all costs. Furthermore, don't be too greedy with boosts and let Raikou get worn down into a range where it can be revenge killed by priority.
Team Options
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Pokemon to take out pesky Excadrill, Hippowdon, Mamoswine, and Choice Scarf Garchomp are heavily appreciated. Offensive Water-types, such as Keldeo, Manaphy, and Greninja, are standout options. Eliminating Chansey is also necessary; the aforementioned Keldeo as well as lures such as Knock Off Landorus can succeed at this role. If Substitute is chosen, then Pokemon to take out Mega Venusaur are mandatory; Landorus and Mega Charizard X are both adept at this task.
Choice Specs
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name: Choice Specs
move 1: Thunderbolt
move 2: Volt Switch
move 3: Hidden Power Ice
move 4: Extrasensory
item: Choice Specs
evs: 32 HP / 252 SpA / 224 Spe
nature: Timid
Moves
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Thunderbolt provides a strong, reliable STAB option. Volt Switch is decently powerful with a Choice Specs boost, and moreover provides Raikou with a cost-free move that lets it pivot off unfavorable matchups. Hidden Power Ice hits crucial Ground- and Dragon-types for super effective damage. Extrasensory covers Mega Venusaur, which can otherwise handle this set well. Shadow Ball can be decent as a situtational heavier hit on Latios, taking off upwards of three-quarters of its HP, but Hidden Power Ice already 2HKOes, so it isn't overall very useful.
Set Details
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The Special Attack and Speed EVs enable Raikou to outrun Thundurus whilst hitting as hard as possible. The rest is dumped into HP for a tad extra bulk.
Usage Tips
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Volt Switch is generally the spam move of choice, dealing moderate damage and providing a safeguard against poor matchups. Against Ground-type foes, it's typically best to hard switch into a better matchup on the predicted switch so that you don't lose momentum. Thunderbolt should be used to clean and for extra power if it is needed to obtain a KO. Like all Raikou variants, you'll want to watch switching it in. Raikou is prone to being worn down by entry hazards and even resisted attacks. If the foe has a Pokemon such as Thundurus, Mega Pinsir, or Talonflame, you'll want to make sure Raikou isn't brought down to such a range where they can break through it.
Team Options
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This Raikou finds itself at home on offensive teams with VoltTurn cores. Pokemon such as Mega Scizor can form such cores; Mega Scizor specifically can pressure Chansey with Knock Off and generally threaten it, which is necessary for Raikou to break through defensive teams. Defog or spin support is essential to keep it in tip-top shape to handle threats; Skarmory and Mandibuzz can handle threatening Ground-types well and fill this role. Kyurem-B, Keldeo, and Manaphy are options to take care of Ground-types, too.
Other Options
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Aura Sphere would be a great option on Raikou, allowing it to smack threats such as Tyranitar and Mamoswine where it hurts, but it is event-locked to a Rash nature, which restricts it to Choice Scarf sets lest Raikou be outsped by many popular threats, including Keldeo, Latios, and Thundurus. Its movepool is rather shallow, so there isn't much else it can really do.
Checks and Counters
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**Ground-types**: Mamoswine, Excadrill, Hippowdon, and Quagsire are all stellar answers to Raikou, as they take a pittance from its attacks and threaten it with their STAB Ground-type attacks. Choice Scarf Garchomp and Landorus-T are 4x weak to Ice, but can outspeed and OHKO it.
**Physical attackers that aren't hit super effectively by Thunderbolt**: Raikou's disappointing physical bulk means hard-hitting physical attackers, such as Tyranitar and Bisharp, can handle it easily.
**Special walls**: Unaware Clefable stops Calm Mind Raikou dead in its tracks. Additionally, Sylveon, Chansey, and Mega Venusaur (sans Extrasensory) can handle it sufficiently.
**Entry hazards and status**: Stealth Rock, Spikes, Toxic, and burn severely limit Raikou's longevity and general ability to last throughout the battle.
**Latios and Latias**: Both aren't really threatened too much by Raikou in general (though Latios has to watch out for the Shadow Ball 2HKO), able to switch in on most of its attacks and eliminate it with a Life Orb-boosted Psyshock no matter the set.