I played a lot of this format in Gen 8, so I’m confident saying your team needs a lot of work. Ghost is a viable type, but this team needs major improvements to get there. Your team has poor synergy, so I’m going to reconstruct it to better fit Gengar’s strengths.
Gengar
Gengar functions best as a powerful wallbreaker that can threaten would-be problems like Hydreigon and Toxapex. You want immediate firepower; for this reason, I think a Choice Specs set is better than Nasty Plot. Try something like this:
Gengar @ Choice Specs
Ability: Cursed Body
EVs: 252 SpA / 252 Spe / 4 SpD
Timid Nature
- Sludge Wave
- Shadow Ball
- Thunderbolt
- Dazzling Gleam
Sludge Wave is better than Sludge Bomb due to its higher BP. Thunderbolt is this team’s main way of dealing with bulky Water types (e.g. Mantine, Keldeo, Toxapex), while Dazzling Gleam neuters Hydreigon and can chip Tyranitar on the switch.
Specs and max Speed guarantee Gengar will hit fast and hit hard, but you can play around with Modest or even Choice Scarf if you think you could do with more Special Attack or Speed respectively. Focus Blast and Trick are also options for chunking Tyranitar and Chansey, though I find Thunderbolt and Dazzling Gleam more consistent.
Gourgeist
Gourgeist is a poor Pokemon and not necessary on a self-respecting Ghost team. If you’re looking for a bulkier Ghost type, you will want one that aids Gengar’s breaking potential. This makes Corsola-Galar a natural fit.
Corsola-Galar @ Eviolite
Ability: Cursed Body
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Will-O-Wisp
- Strength Sap
- Stealth Rock
- Night Shade
Corsola-Galar is one of Ghost’s few defensive options and provides a healthy backbone for the rest of the team. Stealth Rock puts Pokemon into range of Gengar, while Will-O-Wisp and Strength Sap deter physical attackers. Night Shade lets Corsola-Galar whittle down foes without needing to take away from bulk investment.
Sableye
Sableye is niche but does well on Ghost teams that can’t fit hazard removal, as it prevents the faster sweepers from getting chipped down. Your dual screens set is novel but ultimately less efficient than a basic Prankster Taunt set that stonewalls Toxapex and Corviknight.
Sableye @ Leftovers
Ability: Prankster
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Taunt
- Will-O-Wisp
- Knock Off
- Recover
Like with Corsola-Galar, there’s not much room to deviate with this set, or Sableye will lose much of its efficiency. This combination of moves dismantles stall teams by preventing hazards, providing constant chip damage, and staying healthy. Sableye is less helpful against offense teams but is still appreciated for its ability to block Aurora Veil and burn attackers like Excadrill.
Aegislash
Great choice. Aegislash might be the best Pokemon to have on a Ghost team thanks to its powerful defensive typing and offensive potential. Your set can’t seem to choose between offense and defense, though — you’ll want to fully commit to make Aegislash most effective. Below are two possible sets you can play around with.
Aegislash @ Weakness Policy
Ability: Stance Change
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature
- Swords Dance
- Shadow Sneak
- Close Combat
- Iron Head
Smogon’s suggestion for offensive Aegislash is probably its best option, as Aegislash has ample opportunity to set up Swords Dance and go to town. Shadow Sneak gives your team a much-needed priority move, while Close Combat and Iron Head address would-be counters like Bisharp and Grimmsnarl. Shadow Claw is typically inferior to Shadow Sneak; your teammates can cover the difference if you need stronger Ghost STAB.
Aegislash @ Leftovers
Ability: Stance Change
EVs: 252 HP / 252 SpD / 4 SpA
Calm Nature
- King’s Shield
- Toxic
- Substitute
- Shadow Ball
This set takes Aegislash in a defensive direction that aims to whittle down fat teams with Toxic and Substitute. Shadow Ball targets Pokemon that wall this combination (e.g. Hatterene, Ferrothorn), and the EVs are allocated to make Aegislash a premier special wall. You can go with max Defense as well, but I think it’s unnecessary when Corsola-Galar handles physical attackers.
Your initial team idea seems to favour offense, so I would recommend the first set, but try out both and see which one you like better!
Decidueye
Your set for Decidueye isn’t good, but Decidueye isn’t worth salvaging in the first place. You should use Dragapult, one of Ghost’s best attackers, to act as a late-game cleaner that picks off opponents weakened by Stealth Rock and Gengar.
Dragapult @ Choice Scarf
Ability: Infiltrator
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Draco Meteor
- Shadow Ball
- Fire Blast
- U-turn
Scarfed Dragapult is one of the fastest Pokemon in the meta, outspeeding Zeraora and Sand Rush Excadrill. This makes it great as a revenge killer, with powerful STAB options in Draco Meteor and Shadow Ball. Fire Blast is great against Ferrothorn and Corviknight and was chosen over Thunderbolt thanks to Gengar already being able to handle Water and Flying types. U-turn preserves momentum and helps the frail Gengar come in safely.
Froslass
Using Froslass means using Spikes, which makes your team into a hazard stack offense when coupled with Corsola-Galar’s Stealth Rock. This isn’t a bad thing, as Ghost teams are effective spinblockers, but Froslass offers little of value outside fast Spikes. If you’d like to retain it, try this set:
Froslass @ Focus Sash
Ability: Cursed Body
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
- Spikes
- Taunt
- Icy Wind
- Destiny Bond
Froslass is near-guaranteed to set up at least one layer of Spikes thanks to Sash + its high Speed. Taunt is useful for negating other leads’ attempts to set up. Icy Wind pairs well with Destiny Bond after Froslass has exhausted its hazard-related usefulness.
If you don’t want to use Froslass, which is understandable given its frailty and lack of meaningful offensive presence, opt for Mimikyu instead. It gives your team a much-needed Dark resistance and offers powerful Fairy STAB to ease the Dragon matchup.
Mimikyu @ Life Orb
Ability: Disguise
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Swords Dance
- Play Rough
- Shadow Sneak
- Drain Punch / Wood Hammer
Disguise gives Mimikyu a free turn to do whatever it wants, which is greatly appreciated against pretty much everything. Life Orb + Swords Dance are necessary for meaningful damage coming off Mimikyu’s base 90 Attack. Play Rough and Shadow Sneak are the STAB moves of choice; like Aegislash, Mimikyu doesn’t need strong Ghost STAB to be useful. Drain Punch gives Mimikyu insurance against Life Orb chip and hits Steel types. Wood Hammer can be used if you really hate bulky Ground teams, but its recoil coupled with the Life Orb generally makes Mimikyu not long for this world.
And there’s the team! I did my best to keep the core idea of your team intact, but modified your sets and Pokemon to better fit Gengar’s strengths. If you like this team, you can find an importable version (with offensive Aegislash and Mimikyu) on Pokepaste.
Good luck and have fun!
