olleh
I'm going to recommend building a hyper offense Dracozolt team. Dracozolt has the ability hustle, multiplying its physical attack by 1.5, but lowering its accuracy by 20%. However, you can ususally dynamax(max moves never miss) and keep the attack bonus while negating the accuracy nerf. Here's the set:
Dracozolt @ Life Orb
Ability: Hustle
EVs: 252 Atk/4 SpD/252 Spe
Jolly Nature
-Bolt Beak
-Dragon Claw
-Protect
-Fire Fang
I'm not sure what seismitoad is here for. Stage hazards are almost completely useless in VGC as matches at max only swich about 4 times, excluding if a pokemon dies. Poison Point is also relatively useless as stalling is also pretty useless because it takes about 4-10 turns in total for a game to end, definitely not enough time to stall your enemies to death. The only reliable chip damage you'll get is from G-Max Cannonade or G-Max Volcalith.
Milotic is pretty good, thanks to competitive, since Dracozolt does not appreciate intimidate, although I'd give it hypnosis as well as coil for the defense boost over ice beam and substitute. Also put wiki berry on it.
Sylveon is also pretty solid although I'd give it pixie plate and quick attack over wish.
Gengar is much too fragile to run black sludge, give it sash. I'd also give it icy wind to drop speed as well as hypnosis and taunt. Sludge Bomb is the only move I'd keep.
Porygon-Z is really good but can't really be used here as it is really only viable if the entire team is built around it, so I'll suggest removing it. A redirector here, such as clefairy or amoonguss, would be really good. Follow Me can completely stop Dracozolt from taking any damage.
Clefairy @ Eviolite
Ability: Friend Guard
EVs:252 HP/252 Def/4 SpD
Relaxed Nature
-Helping Hand
-Follow Me
-Protect
-Moonblast
Arcanine is solid. I'd definitely invest a lot more into speed though, and protect over morning sun. Also, Sitrus Berry-Arcanine isn't bulky enough to have wiki.
You'll generally want to lead Dracozolt and Clefairy, or if the enemy outspeeds Dracozolt, lead Gengar instead of Clefairy. If the enemy has an intimidater, you'll want to bring milotic, if not, you probably want Arcanine and finally, have Sylveon in the back as a cleaner.
Oh, and a pokepaste: Pokepaste
Hope I helped!
Edit: my spelling is absolute crap lol