I apologize if my earlier response to Choice Band Ho-Oh was inadequate. Let's take a good look at some ways of dealing with Scarf Koygre:
Palkia
Abilities: Pressure /
Telepathy
Base Stats: 90 HP / 120 Atk / 100 Def / 150 SAtk / 120 SDef / 100 Spd
Perhaps the premier answer to Kyogre this generation, Palkia has always been able to comfortably absorb Kyogre's Water attacks, and tank it's other attacking options, usually Thunder and Ice Beam.
Generally, Palkia will run something like this:
Palkia @ Assault Vest/Lustrous Orb/Choice Specs/Choice Scarf/Other
Ability: Pressure
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature
- Spacial Rend
- Thunder/Thunderbolt
- Surf/Hydro Pump
- Flamethrower/Fire Blast
Palkia's typing, and wonderful base stats allow it to do many things. It can tank a hit and outspeed Scarf Kyogre if it wears a Choice Scarf of its own and fire off a Thunder. It can tank a hit and fire off extreme damage if it puts on a pair of Choice Specs and uses Thunder/Spacial Rend. it can do strong damage if it wields a Lustrous orb, tanks a hit and attacks. And finally new to this generation, it can absorb an attack with much greater ease and fire back an attack if it wears an Assault Vest. When you throw in Palkia's amazing coverage, speed, and power, Palkia is not only a Kyogre check, but a Pokemon which can glue your team together and provide tremendous offensive pressure and wall breaking prowess.
All of these scenarios assume Palkia merely switches into Kyogre at any point in the game. If Palkia is switched in at full health, say after Kyogre gets a KO, it will almost always beat Scarf Kyogre 1v1. Each set can do prominent damage to Scarf Kyogre at the cost of around 30% of health per non-water. 'Ogre attack. Alas, Palkia is not without its share of weaknesses. Chief among them is Palkia's lack of reliable HP recovery, as well as how much Palkia loathes being hit by Thunder, and then the thunder causing Paralysis. Also notable is Palkia being unable to resist powerful Dragon and Fairy attacks from a teammate of Scarf Kyogre e.g. Xerneas.
Still, if you're looking for an all-around Kyogre check, Scarf or No scarf, Palkia should be top on an Uber player's list.
Another interesting Scarf Kyogre/general Kyogre check is Arceus Electric:
Arceus-Electric
Abilities: Multitype
Item: Zap Plate
Base Stats: 120 HP / 120 Atk / 120 Def / 120 SAtk / 120 SDef / 120 Spd
Arceus Electric can serve as both a Kyogre check and overall support, having base 120 stats across the board, a wide movepool, and a powerful STAB option in Judgement. It's resistant to the Water and Electric moves that Kyogre dishes out, netting it many opportunities to come in on the leviathan.
Because it will be unable to outspeed Scarf Kyogre, perhaps the best way to outright win against ScarfOgre would be to run a set like this:
Arceus-Electric @ Zap Plate
Ability: Multitype
EVs: 252 SAtk / 252 Spd or SDef or HP/ 4 in anything else.
Timid Nature
- Judgement
- Ice Beam
- Calm Mind
- Recover
Because of Electriceus' uniform base 120 stats, you're free to put EVs into whatever you think is best. However, Calm Mind + Recover lets Arceus-Electric not only switch into Kyogre and attack, but also set up or heal itself. Pseudo bolt/beam coverage lets this Pokemon also do a sizable amount of damage to just about any switch-in, and net a trainer quite a bit of offensive pressure. You can even replace one or more of the moves above with utility moves like Defog, Will-o-Wisp, Roar, or Toxic. Truly, Arceus-Electrics's resistances, stats, versatility, utility, and more let it be one of the most interesting choices for facing Scarf Kyogre, or Kyogre in general.
