Well these are rumors and myths about pokemons, from one gen to another. Some of them are sad and some of them are just interesting. For some reason those myths have caught my attention.
Well here I go?
When a Kagaskhan mother is killed, her baby remains orphan. Because of this the baby needs to defend itself without the help of its mother. It takes the skull of its mother and uses it as type of helmet/mask. The bone it uses in battle is long bone (like a leg) perhaps. With these it can fend off other pokemon who may try to attack it. Like a Raticate and Rattatas.
After the games Red and Blue it’s pokedex info changes, proving that the theory is true in a way but it does not confirm that it is INDEED the orphan baby of a Kangaskhan.
Yellow Wears the skull of its deceased mother. Its cries echo inside the skull and come out as a sad melody.
Stadium Always wears the skull of its deceased mother on its head and never shows its face. It cries mournfully in the moonlight.
But people also theorize it as cubone being a mourning charmander. Due to the shape of the skull it wears and the way charizard’s head is shape, a little bit similar to cubone helmet/mask. Though it is mostly believed to be a Kangaskhan’s orphaned baby.