Mienshao

Mienshao's introduction to Pokemon Go is unfortunately highly disappointing for the metagame. 258 ATK is very respectable, but this gets thrown out the window rather quickly when Mienshao's horrible moveset is made obvious. Low Kick and Brick Break are among the bottom of the barrel in the world of Fighting-type moves in Pokemon Go, and thus a moveset update is mandatory if Mienshao is to be anything more useful than a dex entry. 

Best PvE Offensive Moveset

• Low Kick is the fast move of choice for offense thanks to STAB.
• Poison Jab isn't bad, but doesn't synergize with a Fighting-type Pokemon. 
• Grass Knot is the strongest charge move against neutral opponents, or when Super Effective. 
• Brick Break synergizes with Mienshao's Fighting-type role, but isn't very strong. 
• Stone Edge doesn't have much use for offense. 

Best PvE Defensive Moveset

• Poison Jab is better for defense, and can hurt Fairy-type attackers as well.
• Low Kick is more likely to be resisted on defense.
• Blaze Kick is the best Charged Move on defense for its high power and great complimentary coverage.
• Brick Break can be used frequently as a 3-bar move, but its STAB damage is lackluster.
• Grass Knot doesn't really threaten Mienshao's weaknesses. 
• Stone Edge hits fast and hurts Flying-types, but Mienshao might faint before it can use it. 

Despite not benefiting from STAB, Poison Jab is chosen over Low Kick due to its superior stats in both damage output and energy gains. 

Brick Break costs the least amount of energy, is useful for baiting shields, and deals decent STAB chip damage for Mienshao's Fighting-type role. Grass Knot provides coverage against popular Water-types in the meta, with a moderate energy cost. Stone Edge requires slightly more energy, but its coverage is wider and also threatens Mienshao's weakness to Flying-type Pokemon.