If this is singles (and often even when it's not) the gen 4 Shiny CROWN Raikou (with Aura Sphere and Weather Ball) can be an excellent counter to practically all weather. Sure, it's locked into a Rash nature (+SAtk, -SDef), so it loses a little effectiveness speed-wise, but it's still a force to be reckoned with. With the following set, it can OHKO Tyranitar, most Politoed, Abomasnow, and deal heavy damage to Ninetales in each summoner's respective weather. Additionally it can abuse sun as well to take out common Chlorophyll abusers with an epic effectively base 150 (cuz sun boost too) fire type Weather ball off a SAtk of 361, which puts even most fire types within KO range. Rain abusers in general can be dealt with either with Thunderbolt or HP Ice while Sand and Hail abusers fall to Aura Sphere. Proper prediction is still needed, but Raikou can still rip through many weather teams.
Raikou @ Expert Belt/Life Orb
Trait: Pressure
EVs: 252 SAtk / 4 SDef / 252 Spd or 4 HP / 252 SAtk / 252 Spd
Rash Nature (+SAtk, -SDef)
- Aura Sphere
- Weather Ball
- Thunderbolt
- Hidden Power [Ice]
Life Orb can be used over Expert Belt, but it doesn't net too many extra KOs and shortens Raikou's lifespan. It does hit a few pokemon like Ludicolo harder with LO, but not too many. Raikoi usually has an option to hit Super-Effectively. Beware of some specially bulky mons, like the ever-present Blissey/Chansey, and threats like Hippowdon who can tank a HP Ice and KO back with EQ. Also, choice scarves usually spell the end for this set due to the lack of a +speed nature in addition to Raikou's mediocre defenses. Also note that this set's function is primarily as a weather summoner counter that can deal with switches to most abusers. You will often have to predict counters to Raikou or walls rather than switches to abusers of the curent weather (though late-game Chlorosaur is generally easy to see coming and KO in the switch-in with Weather Ball). With practice, I have been able to reliably take out these counters and use Raikou as a sweeper as well on my sun team, making him more useful than simply as a niche set.