Just here to drop in a short heat post about rain:
Poliwrath is surprisingly powerful in rain.
Poliwrath @ Mystic Water
Ability: Swift Swim
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Liquidation
- Belly Drum
- Close Combat
- Darkest Lariat/EQ/Encore
the process is quite simple:
1.slow pivot poliwrath into something that is forced to switch
2.belly drum on the switch
3. ???
4. smash everything
If you know how powerful of a breaker shifu-rs is on rain, then it should come as no surprise that a belly drummed up poliwrath on rain is like urshifu-rs from hell on crack, being insanely fast, and hitting like a truck loaded with smaller trucks loaded with bricks. It shares urshifu's typing, which is actually amazing for its role since it resists ice shard, bullet punch and sucker punch, which combined with its very decent for an offensive mon bulk of 90/95/90 makes it actually very hard to revenge kill. Oh and also unlike banded shifu, this guy can swap moves so you can't even exploit it being locked. It can either punch holes in the opposing teams if you bring it out early, or sweep late as necessary.
moves:
1. liquidation is pretty straight forward, spam this move unless you see some reason not to like a very very sturdy resist or absorb
2. cc, 120 bp STAB move coming off a belly drum is pretty bonkers, ngl. Fighting stab is also great for rain teams, as IMO every good rain team needs a way to get rid of ferro that is not barraskewda banded cc, since that is too exploitable
3. belly drum, its what makes the whole set tick, if you get this off you become an utter menace that is almost guaranteed to get a kill(probably several)
4. here is the coverage move: EQ for pex, darkest lariat for bro, encore to make setting up on slow mons easier, you should pick according to what you run into on the ladder most often.
I'm too lazy to calc stuff, but if you don't understand that +6 STAB water moves in rain hurt a lot, then I don't know what to say
it should be noted that stupid monke makes poliwrath cry, but then again it makes a lot of things on rain cry, and it's not that popular lately.
EDIT: it has been brought to my attention that kyurem also makes rain cry, but poliwrath hates stupid rain bullies and so he will make stupid kyurem cry with Close combat(81.3% of the time, if kyurem is full hp)
Also I didn't come up with this, but yoinked it off some dude who owned me on ladder with it a few months back, so shoutouts to some dude on the ladder!
replay(there is only one, since people like making replays private, might add more later if I run into someone who won't make the game private):
https://replay.pokemonshowdown.com/gen8ou-1419996358 - if you look very closely(blink and you'll miss it), you can see poliwrath tearing a whole relatively standard team structure apart with his bare glowed three fingered hands; first coming in on ferro to drum and breaking the necks of chumps torn and kyurem; and even coming back later without a belly drum(!!!!11!!!1!) to finish off ferro and severely damage lando and glowking. It did approx. 80% of my entire team's damage that game.
for closing words I'm just gonna leave a pic of poliwrath after it gets off a belly drum in the rain:
View attachment 373142(guess this wasn't that short after all)
(Ground)
Mixed SD Garchomp 
