Shadow Gengar

It took until the Halloween season of 2023 for the game's original shadow to get a Shadow forme, but it's made up for lost time.

Honestly, Shadow Gengar is great, but it has issues. Namely, it dropped in Pokemon Go just a bit too late to be the king of slaying Psychic Types and its fellow Ghost Types. This is because Shadow Tyranitar in particular has substantially more TDO while also sporting similar DPS in most cases, meaning Shadow Gengar cannot be seen as the undisputed best within its niche most of the time, especially given its outright weaknesses to Ghost and Psychic Type attacks.

So does this mean that Shadow Gengar is bad? Not by any means! Shadow Gengar rises to the same niche as its basic forme, as the premier glass-counter to anything with a weakness to Ghost. It's an explosive Pokemon with outstanding damage output, but keep in mind that it's also likely to explode pretty quickly itself.

Worth noting; the Shadow Claw vs Lick argument is a bit more pronounced with Shadow Gengar than its basic forme. Shadow Gengar generally won't be on the field for very long, but its potential damage output is through the roof. For this reason, getting out one additional Shadow Ball due to Lick's higher energy generation can make a pretty substantial difference.

Best PvE Offensive Moveset

• Shadow Claw is a strong attack with decent energy gain. 
• Lick *is also a strong attack with less power, but faster energy gain than Shadow Claw. Both perform similar DPS, though Lick does tend to pull ahead.
• Hex and Sucker Punch are quite close in performance; the main difference is that Hex is resisted by fewer types.
• Shadow Ball is Shadow Gengar's best charge move, sharing the same type as its best fast moves.
• Sludge Bomb also has STAB, but its Poison typing lacks synergy with Ghost-type attacks. You're going to want to pair it with Lick for superior energy generation.
• Focus Blast has niche uses vs. Normal-type foes, but overall is an inferior option.
• For Shadow Gengar's legacy moves, Sludge Wave has the same problem as Sludge Bomb's lack of type synergy in addition to being a 1 bar move that doesn't complement Shadow Gengar's frailty.
• Dark Pulse is generally awful and offers almost no advantages over Shadow Ball.
• Psychic is a good charged move, but it has no utility on Shadow Gengar.
• Shadow Punch, Shadow Gengar's Community Day move, is too weak to be useful on offense.

Best PvE Defensive Moveset

• Defending with a  Shadow Gengar is not advisable due to its very low bulk. That said, Hex hits the hardest and is therefore optimal.
• Shadow Claw has less power and less energy gain than Hex. Don't bother with Sucker Punch.
• Psychic* is a good option, though it doesn't offer much counter-coverage.
• Sludge Bomb and Dark Pulse both have 2 bars and are difficult to dodge; the former is benefited by STAB.
• Shadow Ball is powerful and narrowly resisted, but can be seen coming from a mile away.
• Focus Blast and Sludge Wave are unusable; Sadow Gengar will generally not survive to use them. 
• Shadow Punch is great on defense thanks to its low energy cost, STAB, and narrowly avoided typing.

Shadow Claw is the superior fast move in both damage output and energy generation. Don't use any other fast move.

Shadow Punch is a charge move limited to Community Day or Elite TMs, but is essential for baiting shields due its low 35 energy cost. Shadow Ball is Shadow Gengar's most efficient charge move in terms of Damage Per Energy (DPE), has incredibly high damage output with STAB and Shadow Gengar's high ATK stat, and hits most Pokemon for neutral damage. Focus Blast can be chosen as an option to fight against Dark and Normal-type Pokemon meant to counter Shadow Gengar, but its high energy cost makes it difficult to access. Sludge Bomb is generally not recommended, but can still be useful in certain formats to threaten Fairy-type Pokemon.