I think the relationship between the twins and the spooky environment might be a key element. Maybe they live in a creepy old house and there are always unexplained events there.
One common element is an air of mystery. Since they are twins, people often expect them to be very similar, so when something strange happens with one or both of them, it creates mystery. For example, if one twin acts completely different all of a sudden. Another element can be a spooky setting like an old house or a dark forest. In many stories, the twins are in a place that gives a feeling of unease. Also, there's often a sense of the unknown, like they might be possessed or have some special connection to the supernatural.
Maybe friendship is a key element. Since they are twins, they are likely to have a very strong friendship. They might rely on each other a great deal.
There are several elements. Firstly, there's the element of the unexpected. Things that happen suddenly and out of the blue, like a door slamming shut on its own in an empty house. Then, there are the sounds. Eerie sounds like howling winds, creaking floorboards or a strange whisper in the dark. Also, the sense of isolation is key. When the characters are cut off from the outside world, it intensifies the feeling of danger and fear.
The Big Mouth Twins themselves are a key element. Their big mouths could be a characteristic that plays an important role in the story. Maybe they use their big mouths to tell big, exciting Christmas stories to the other kids in town. Also, presents and gift - giving could be an element as it's an important part of Christmas.
The key elements might involve the family background of the twins. If they come from a large family or a family with a special situation. Also, their personal achievements. For instance, if they are both excellent students or athletes. And of course, the reason why their story was featured on 'Good Morning America' in the first place, which could be something really remarkable like they started a non - profit organization together.
One key element is their home planet Exxor. It's where they come from and where their powers are rooted. Another is the exchange program that brought them to Earth. This is important as it sets the stage for their adventures with the Super Friends. Also, their distinct powers - Zan's water - based transformations and Jayna's animal shape - shifting are crucial elements of their origin story.
As I don't know the particular 'Carmen scary story', generally, key elements in a scary story could be a spooky setting. For example, if it's set in an old, abandoned place like an old asylum or a decrepit cemetery.
Since we don't know the exact story, but generally, a key element could be the handkerchief itself. It might be an object with a strange appearance, like being made of old, tattered fabric or having some unusual markings.
As I don't know the exact Jenna scary story, generally, a key element could be Jenna herself as the source of fear. Maybe she has an eerie appearance like pale skin and dark, sunken eyes.
One key element could be suspense. It builds up the tension, like when you hear strange noises but don't know what's causing them. Another might be a sense of the unknown. If there's a mystery figure in the story, not knowing who or what it is makes it scarier.