Shadow Poliwrath

Mud Shot + Dynamic Punch and Ice Punch or Scald

Mud Shot features the best energy generation in the game.

Due to the nerf of Power-Up Punch (PUP) from the September 2019 rebalance, the strategy of spamming PUP is no longer viable, and Dynamic Punch is more preferred for Fighting-type damage. Ice Punch is valuable for its lower energy cost and coverage, including against Poliwrath's weakness to Grass and Flying-types. Hydro Pump is more viable with this moveset's fast energy gains, and can possibly OHKO opponents when shields are down. Scald offers a more consistent option to deal Water-type damage due to its lesser energy cost, though the potential of applying a debuff should be considered as gravy on top instead of a consistently reliable strategy. 

Bubble + Ice Punch and Power-Up Punch or Dynamic Punch or Scald

This moveset is similar to the previous one, but provides more consistent Water-type damage from Poliwrath's fast move. Bubble is also more efficient at farming opponents with low HP, since Mud Shot has poor damage output. Power-Up Punch (PUP) can be useful for ramping up damage of Poliwrath's other moves (including its fast move), though Dynamic Punch has seen increased usage following the nerf of PUP.