Shadow Poliwrath

Shadow Poliwrath is not generally worth considering for raids or gyms. While its performance is definitely stronger than its base forme in raids, that performance still is not very impressive for its high cost. As for defense; it doesn't appreciate the drop in defense, and is generally inferior to its base forme. The addition of Counter is appreciated and Shadow Poliwrath isn't terrible per se, but other Fighting attackers are still superior.

Best PvE Offensive Moveset

• Poliwrath needs Counter for Fighting-type offense.

• Rock Smash is another option but it is significantly worse.

• Bubble pairs well with Hydro Pump, but there are better Water-type attackers out there.

• Mud Shot lacks STAB, power, and coverage.

• Dynamic Punch is one of the best charge moves out there, period, and strictly outclasses Submission.

• Ice Punch and Icy Wind are not great charge moves in a vacuum and lack STAB to boot.

• Scald is a poor move for PvE.

• Return has no use on an offensive Poliwrath.

Best PvE Defensive Moveset

• Counter is the best overall move on defense.

• Rock Smash does slightly more damage on defense than Bubble does, but has lower energy gain.

• Mud Shot is useless on defense due to its low power.

• Ice Punch hits many of Shadow Poliwrath's counters effectively, and it fires frequently due to having 3 bars.

• Icy Wind is also 3 bar and a bit stronger than Ice Punch, but it's easier to dodge, which makes it comparable. 

• Dynamic Punch is a great option with high power, STAB, and 2 bars. Submission is strictly worse.

• Scald is a slight downgrade in terms of damage and speed, but still decent overall. 

• Hydro Pump punishes attackers who fail to dodge, but it may not be used at all.

Counter is a solid Fast Attack and Poliwrath has STAB on it. While Mud Shot and Bubble aren't bad Fast Attacks, Counter is just too good to pass up on most of the time.

Various charged attack combinations are viable depending on team needs. Any combination works, except for Power-Up Punch + Dynamic Punch or anything involving Hydro Pump or Submission.

Icy Wind provides coverage against Flying-, Grass-, and Dragon-type Pokemon and provides a guaranteed Attack debuff. Ice Punch provides the same coverage and is cheaper, but is inferior due to the lack of debuffing.. Scald benefits from STAB and provides additional coverage against targets that Counter cannot deal significant damage against. Power-Up Punch can ramp up Counter's damage to absurd levels in the long game, but sacrifices coverage and burst. Dynamic Punch can be used to further bolster Poliwrath's Fighting-type damage, although Counter is usually enough.  Hydro Pump is generally too expensive. Submission is outclassed.