Halloween is not celebrated widely in New Zealand and never heard of it when I was back in India.
But some years ago the mall close to where I live (in NZ) hosted a Halloween party for kids - the idea was to keep kids supervised in a safe environment, off the streets and out of the cold and wet (the weather here is so unpredictable).
This was my son's first Halloween. He dressed up as Batman and his "loot catcher" was an ordinary plastic bag with a picture of a pumpkin that my daughter pasted on.
He was so cute. As we walked from shop to shop he whispered trick or treat - so quietly you could barely hear him. The sales people in the shops just loved him. He came home with a lot of loot.
Unfortunately that was the only year the mall did a Halloween party. So that was really the only one we ever participated in.