Gengar is Gengar really. It's the Shadow Pokémon, and I find it just fits this theme pretty well. Many Ghost- types were in my mind at the time, like Cofagrigus, but I felt this would probably be the best option.
Conkeldurr resembles a Clown, and actually has solid synergy with Gengar. It can take on most dark types with ease. For this mon, I have the lure set. Pretty cool for beating Clefable.
Gourgeist resembles a Jack-O-Lantern. Despite it stacking common weaknesses with Gengar, it actually beats a few of the premier threats to my team. It can 1v1 most physical threats like Scizor, Garchomp, Landorus-Therian, etc. That's it main niche on this team; handling physical attackers. It also fits the theme of this competition!
Delphox resembles a witch. I felt it worked nice as a set up sweeper for this team. I feel that Delphox is actually a cool mon, and wanted it to fit on any one of my OU teams. On this team, it seems to fit well. It targets most fighting types, and actually does a ton of work behind a sub and/or with a Calm Mind up.
Zoroark is one of my favorite Pokémon in the series. Now, I don't know how it fits here other than it fits in the trick part of Trick-Or-Treat, since it uses the Illusion ability, tricking opponents. Now my team lacked a choiced mon so far, so I slapped a scarf on this thing.
I felt Tyranitar fit much better than Zoroark for reasons that aren't just fitting with the Halloween theme. It checks Lati@s for my team, as well as Talonflame. Looking at it again, my team struggles against Talonflame! However Tyranitar can ease that struggle.
Golbat... Now, why Golbat over something like Crobat? It is the evolved form of Golbat, no? Well, my friend, Digital Edge, discovered something rather interesting about Golbat. It can check Mega Lopunny very well, taking hits easily and dealing tons of damage back. It can remove the hazards too, which is what I was looking for.
I'll explain each thing that isn't 'standard'. Conkeldurr has 124 speed EVs to outspeed Clefable, which allows it to efficiently outspeed and KO with Poison Jab. There isn't a reason for Gourgeist's somewhat mixed defenses, but it gives it max SpDef bulk as well as some physical bulk instead of just max / maxing HP and SpDef. Leech Seed provides great residual damage, and gives solid recovery when combined with Leftovers. Will-O-Wisp cripples majority of the physical attackers, and even deals a lot of damage when you combine it with Leech Seed. Delphox is cool, packing a Sub CM set. This beats stuff like Breloom (if doesn't have sash + rock tomb), Venusaur, Amoonguss, etc. Golbat is actually cool. It checks Mega Lopunny well, only being 3HKOd by Ice Punch and/or Return. It can 2HKO with a Brave Bird, while Super Fang cripples bulkier threats that Golbat wouldn't be able to touch otherwise (like Skarmory). This team struggles against Mixed Attacker Thundurus, so keep that in mind. Try and keep Tyranitar alive so it can KO with Stone Edge, or keep Gourgeist at a reasonable amount of HP to beat it. Tyranitar checks electrics like Mega Manectric, while also checking Lati@s. Team is actually 17 - 4, did not expect it to get 17 wins but ok (do /rank halloween squad). >.>