This one wasn't requested but I wanted to do something a little special!! This one will be quite short but it's their costume, your costume and what you do! Ps I know this is a little early :/
Gon
Gon is a sheep?? I think?? Well actually GON WOULD MAKE SUCH A CUTE CATBOY AHHHHHHHHHHHHHHHHHHHH but if Gon went as a catboy, you'd also be a cat. If he went as a sheep like in the mobage you'd be a cow!
You go trick or treating around whale island, and afterwards you trade your candy at home ;)
Killua
Killua would be a vampire! That would make the two of you, and I think Killua would pretend to suck your blood at least once.
Your first go see if you can get some chocolate robots at the candy store, then you'd go trick or treating too!
Kurapika
Kurapika is a mummy! Head cannon Kurapika would want to match with whatever you're dressing up as, but in the mobage he's a mummy :(
The two of you would go to send off Gon and Killua to trick or treat, then you'd go home and watch scary movies together! Kurapika gets a little scared so make sure you watch over him!
Leorio
Leorio is going as a werewolf, THIS IS SO CANNON AHHHHHHH! I wouldn't change this one at all. Since Leorio is going as a werewolf you're going to go as a Vampire <3 OPPOSITES ATTRACT!!
You both would go around hospitals giving candy to kids in the ICU, or kids who aren't fortunate enough to leave the hospital yet :)
Illumi
Illumi is going as a zombie! I watched a video on this before, I think it's a Chinese zombie? But I wouldn't change this either! I think it matches so well with his nen ability. You'd also go as a zombie!
The two of you would go steal some candy and stalk Killua <3
Hisoka
Hisoka is going as a joker! I think maybe you could go as a circus ringmaster, or a magician to match him.
You would run around stealing kids' candy.
Morel
I couldn't find a mobage card for him :( but I think he would make a good Frankenstein! You should probably go as a Frankenstein too.
He would probably take you to buy candy for Gon and Killua, and afterwards take you to a Halloween party!
Colt
Colt doesn't have a mobage card either :( he could probably go as a chimera ant lol and you could go as whatever you want!
You're both going to Morel's Halloween party!
Chrollo
Chrollo is going as a security guard or a vampire! That means you'd go as a security guard/prisoner or a bat!!
You'd both go on a dinner, maybe hit up a party, watch a movie, or maybe just steal some candy!
Meruem
Meruem doesn't know what Halloween is, so I don't think you'd go. The both of you are staying home and watching as many Halloween movies as possible, he needs to be educated!
Feitan
Feitan is the grim reaper, how fitting! I think maybe you'd go as a ghost then :)
The both of you are out stealing candy, trick or treating, or basically anything you want to do!
Machi
Machi is a police officer! BLM, but remember acab is for the American police system so Machi is okay :)
You'd probably be a prisoner then.
You'd make sure Hisoka doesn't get into too much trouble lol