Dusknoir

With mediocre stats both offensively and defensively, as well as a suboptimal movepool, unfortunately Dusknoir will be only worth the Pokedex entry. It’s at least kind of bulky and resistant to Machamp.

Best PvE Offensive Moveset

• Hex marginally beats Astonish.

• Shadow Ball is the best Charge move available, but is limited to Community Day events and Elite TMs. 

• Ominous Wind’s STAB is compensated by Dark Pulse’s better parameters.

• Psychic and Dynamic Punch have no offensive use on Dusknoir.

Best PvE Defensive Moveset

• Hex is again the better fast move.

• Psychic is a great option with good power and 2 bars, but it leaves Dusknoir easily picked off by Dark-type attackers. 

• Ominous Wind can be used frequently with 3 bars, but Dark Pulse is stronger and harder to dodge.

• Shadow Ball is the slower and harder-hitting option, and isn't a bad choice considering its limited availability. 

• Dynamic Punch is a strong Charged Move with coverage against Dark Types.

Astonish is preferred over Hex due to its high damage output; Dusknoir's energy costs are low enough to not require Hex's energy gain.

Shadow Punch is a cheap-costing STAB move with decent overall damage output. Dynamic Punch offers nigh-unresisted coverage when combined with Dusknoir's Ghost STAB. Shadow Ball*, Dark Pulse, Psychic, Poltergeist, Ominous Wind, and Return are all outclassed - either due to redundant coverage, low DPE, or high energy costs.