Golduck Rain with more serious option at the bottom,

Pelipper @ Damp Rock                                 Rain Setter
Ability: Drizzle                                     Sets rain for team, so keep alive, hurricane is nice against bulky grass
EVs: 248 HP / 196 Def / 64 SpD                       which the team struggles with, and scald is nice to burn physical threats and
Bold Nature                                          wear down walls. Uturn is there so peliper can act as a defensive pivot
- Hurricane                                          bringing in the rain sweepers with minimal damage taken.
- U-turn
- Roost
- Scald

Golduck @ Psychium Z                                 Rain Sweeper No.1
Ability: Swift Swim                                  Z-Psychic is there to help beat toxapex after small prio damage
EVs: 4 Def / 252 SpA / 252 Spe                       252+ SpA Golduck Shattered Psyche (175 BP) vs. 252 HP / 24 SpD Toxapex: 244-288
Modest Nature                                        (80.2 - 94.7%) -- guaranteed 2HKO after Black Sludge recovery. Focus blast
IVs: 0 Atk                                           2hkos ferrothorn on switch most of the time and hydro is main stab doing most a
- Hydro Pump                                         damage to switch ins. Ice beam is there to hit dragon types which resist your
- Ice Beam                                           main stab
- Psychic
- Focus Blast

Kabutops @ Life Orb                                  Rain Sweeper No.2
Ability: Swift Swim                                  Aqua Jet is there to help beat priority mons and faster mons as well as hit mons
EVs: 4 HP / 252 Atk / 252 Spe                        outside rain still really hard after an sd. Waterfall and stone edge are main
Adamant Nature                                       Stabs in rain and can help break switch ins when at +2.
- Aqua Jet / Low Kick / Superpower                   +2 252+ Atk Life Orb Kabutops Stone Edge vs. 252 HP / 4 Def Tangrowth: 352-415
- Waterfall                                          (87.1 - 102.7%) -- 93.8% chance to OHKO after Stealth Rock
- Stone Edge                                         Low Kick can be used over aqua jet to cleanly pick off ferro at +2 or superpower
- Swords Dance                                       can be used for immediate power instead of having to boost.

Scizor-Mega @ Scizorite                              Defensive Pivot
Ability: Light Metal                                 M.Scizor acts as a defensive pivot being able to switch in on a multitude of
EVs: 248 HP / 112 Def / 124 SpD / 24 Se              threats, increased by the weakened fire damage, and then can uturn safely in to
Impish Nature                                        a main rain sweepr. Bullet Punch and sd are there to help clean late game when
- Bullet Punch                                       m.scizors checks are beaten or weakened, or to pick off / weaken threats for the
- U-turn                                             main rain sweepers.
- Roost
- Swords Dance

______________________________________________


Tapu Koko @ Leftovers                                Offensive Pivot Option 1
Ability: Electric Surge                              Tapu Koko is there to pick up momentum by forcing mons out to allow a rain sweeper
EVs: 4 Atk / 252 SpA / 252 Spe                       in whilst taking minimal damage. Thunder not being able to miss in rain, tapu koko
Timid Nature                                         is able to deal large damage without the use of a life orb and break bulky water
- Thunder                                            types which the rain sweepers find annoying. Natures Madness is  there to weaken
- Nature's Madness                                   switch ins that the rain sweepers also find annoying such as ferro and other rain
- Hidden Power [Ice]                                 checks. Lastly ice is there to help tapu koko not be walled by garchomp and
- U-turn                                             landorus-t, though pitifully weak without LO. Lefties are used to increase
                                                     longevity as its not needs for main offensive pressure.
or

Tornadus-Therian @ Life Orb                          Offensive Pivot Option 2
Ability: Regenerator                                 Tornadus-T fills the same roll as koko but has increased longevity due to
EVs: 4 Atk / 252 SpA / 252 Spe                       regenerator and bulk, but is not as fast as koko. Tornadus-T can also break bulky
Timid Nature                                         Grass types unlike koko and hurricane is far more spamable due to nothing being
- Hurricane                                          immune. Focus Blast can also help beat ferrothorn for the main rain sweepers.
- Focus Blast                                        Tornadus-T also comes with a different support option on knock off, crippling
- U-turn                                             mons that rely on there items.
- Knock Off

______________________________________________       both pivots can work, its just preference...

Excadrill @ Leftovers                                Bulky Spinner and Setter
Ability: Mold Breaker                                Excadrill fulfils the final requirements for the team. Electric check, spinner,
EVs: 252 HP / 4 Atk / 252 SpD                        hazard setter and is particularly good at it, as it can set hazards against stall
Careful Nature                                       and weaken switch ins with toxic, helping the rest of the team out.
- Stealth Rock
- Rapid Spin
- Earthquake
- Toxic


To alter this into a more serious rain team, give kabutops rockium-z and aqua jet > fighting coverage, and use life orb kingdra mild nature over goldduck with: waterfall, outrage, hydro pump and draco meteor. Tornadus-T and Tapu Koko still interchangeable.

Count Sheep~