Fact: Shayne was born to dress up as Wednesday Addams. In fact the whole concept of the band dressing up as the Addams was so that Shayne could dress up as Wednesday.
BJ could’ve probably worn a bald cap and an overcoat and gone as Uncle Fester, but to pull that off in Florida weather? That would be disastrous. Plus he looks good in stripes.
And Kenny just had the right charm to play Gomez. Putting him in semi-formal wear and attaching a plastic hand to his shoulder was easy. Getting him to grow out and not shave his mustache for the latter half of October was immensely harder. But we do it for the art. Also BJ shaved his beard for the Pugsley baby-face.