One key element is loss. The loss of its mother is crucial as it forms the basis of the story. Another is the love it still holds for its mother, shown by it wearing her skull. And the loneliness that results from this loss, as Cubone wanders alone, is also an important part.
The key elements in the Cubone love story are multi - faceted. Firstly, the love for its mother is at the heart of it. This love was pure and strong, creating a bond that couldn't be broken even by death. Secondly, the loss of its mother is a significant element. This loss led to Cubone's unique situation. It not only lost a protector but also a source of love. Thirdly, the way Cubone expresses its love and grief through its actions, like wearing the skull and its often - solitary behavior, is also a key part of this story. It's a story of love, loss and how a Pokémon tries to hold onto something that's no longer there.
Well, the first key element is the deep - rooted love that Cubone had for its mother. This love was so strong that even after her death, Cubone couldn't let go. The second element is the physical reminder of that love, which is the skull of its mother that Cubone wears. Also, the way Cubone copes with this love and loss in its solitary existence is a key element. It doesn't have other Pokémon around it in the same way, and this solitude is a big part of the story.