Fast Pivot (Chinchou) @ Eviolite  
Ability: Water Absorb / Volt Absorb
Level: 5  
EVs: 52 Def / 228 SpA / 220 Spe  
Timid Nature  
IVs: 0 Atk  
- Hydro Pump  
- Volt Switch
- Thunderbolt / Thunder Wave
- Protect
Set Details: Hydro Pump is Chinchou's strongest attack, and can deal good damage to neutral targets, as well as threatening many water-weak Pokemon such as Ponyta and Onix. Volt Switch is a useful pivot move that allows Chinchou to escape attacks directed at it while dealing damage. Thunderbolt is a stronger Electric STAB that doesn't make Chinchou switch out, and hits Flying types like Vullaby and Rufflet and Water types like Omanyte for massive damage. Alternatively, Thunder Wave can be used to cripple an opposing Pokemon, and is a form of speed control. Finally, Protect is a staple of any Doubles format, allowing Chinchou to evade attacks and give its teammate a free turn, and to stall out terrain conditions.
This set's EV spread maximizes Chinchou's Speed and Special Attack, allowing it to outspeed Rufflet and speed tie with Onix and Mienfoo and hit as hard as possible. Eviolite gives Chinchou the little additional bulk it needs to survive attacks, such as Ponyta's High Horsepower at full health. For the choice of abilities, Volt Absorb allows it to wall Magnemite and switch into Electric-type attacks, while Water Absorb allows it to wall Omanyte and recover HP against opposing Muddy Waters. Chinchou is often itself weak to attacks from Pokemon it can hit super-effectively, such as Ponyta and Onix's High Horsepower, so for Chinchou to be able to outspeed them, Tailwind users like Vullaby and Rufflet make good partners. They can also switch into Ground-type attacks directed at Chinchou and handle opposing Grass types, while Chinchou can switch into Electric-type attacks that threaten them. Ponyta can also threaten opposing Grass types, and with Water Absorb, Chinchou can deter opposing Pokemon from using Water-type attacks to hit Ponyta. Finally, Grass types like Foongus and Grookey also appreciate Chinchou's ability to outspeed and threaten out opposing Flying types, and can help deal with opposing Ground types and in Foongus' case, redirect attacks away from Chinchou to keep it safe.

Bulky Pivot (Chinchou) @ Eviolite  
Ability: Volt Absorb / Water Absorb
Level: 5  
EVs: 76 HP / 212 Def / 68 SpA / 148 SpD
Bold Nature  
- Scald  
- Volt Switch  
- Thunder Wave / Icy Wind
- Protect
Set Details: Scald is Chinchou's main STAB move, and has a nifty chance to burn the target, crippling most physical Pokemon. Volt Switch is a useful pivot move, and with this set's low speed, can be used to bring in a teammate safely. The third slot provides a form of speed control for Chinchou. Thunder Wave can halve the speed of a single Pokemon for the rest of the game, while Icy Wind deals chip damage and slows down both opposing Pokemon until they switch out. Finally, Protect is a staple of any Doubles format, allowing Chinchou to evade attacks and give its teammate a free turn, and to stall out terrain conditions.
This set's EVs, coupled with Eviolite, maximize Chinchou's bulk, allowing it to withstand more attacks, considering its low speed. A little investment in Special Attack allows it to hit Vullaby and Rufflet a little harder with Volt Switch. Volt Absorb and Water Absorb are both good options, and can both provide Chinchou with some much-needed recovery in the right situation. With its bulk, this set can switch into attacks much more often, so Fighting types, like Mienfoo and Scraggy, and Grass types, like Foongus and Grookey, appreciate its ability to switch into Flying-type attacks. The latter two can also deal with opposing Onix, which outspeeds bulky Chinchou. Grookey also gives Chinchou a form of passive recovery with Grassy Terrain, giving it a little more longevity. Finally, Ponyta can deal with opposing Grass types for Chinchou, and enjoys Chinchou providing speed control and threatening opposing Flying-type Tailwind setters.