Question

Warning I cant spell.
Poison is my favorite type so I made a monopoison team.
Nidoking @ blacksludge
Nature: jolly
Evs: 252spd (idk what else to do with the evs make any suggestion)
Moves: stealthrocks, toxicspikes, EQ, and poisonjab
Ability: not sure
Why: its beast, and sets up entry hazards.

Venusaur @ blacksludge
Nature: bold
Evs: 252def 252hp 4spdef
Moves: gigadrain, sludgebomb, leachseed, sleeppowder
Ability: overgrow
Why: its my generic set for venusaur when not in a sun team. Its bulky, puts things to sleep, and can survive with that set.

Gengar @ lifeorb
Nature: modest
Evs 252spatk 252spd 4hp
Moves: toxic, venoshock, shadowball, gigadrain
Ability: levitate
Why: its a spinblocker plus iv wanted to test a venoshock gengar.

Crobat @ blacksludge
Nature: adament
Evs: 252spd 252atk 4spdef
Moves: xscissor, nightslash, bravebird, roost
Ability: not sure
Why: its immune to ground and can hit psychic types supereffectively. With roost and bravebird are a good combo.

Muk @ blacksludge
Nature: carful
Evs: 252spdef 252atk 4 hp
Moves: poison jab, focuspunch, substitute, idk what else
Ability: poisontouch
Why: have you ever tangled with muk? Its not fun

Drapion @ choicescarf
Nature: adament
Evs: 252spd 252atk 4hp
Moves: crosspoison, earthquake, crunch, idk
Ability: sniper
Why: its a good poison type.

Comments

Acid Armor or Shadow Sneak on Muk.

Aqua Tail or Ice Fang on Drapion.

Other than that, I cannot begin to tell where the flaws are.

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Listen you have a good set but I just want to point a couple things out and I hope you realized this too.  First your very susceptible to psychic, ground, and ice type moves so I recommend teaching your pokemon more ghost, fire, and water type moves.  It was smart giving Gengar shadow ball but it won't be very helpful against a pokemon like Alakasam who's speed is much faster then Gengar's.  I like that you have toxic spikes and stealth rocks however, you gave them both to Nedoking spread out your moves to help your pokemon cover their weaknesses.  I'm sure all you pokemon are strong so I hope my advice is helpful and good luck.