What are some of your favorite unsolved mysteries and speculation in the Pokémon games that you want to see further fleshed out in future games. Or just things you feel have been forgotten or unexplored.

Examples:
>Cubone Unmasked
>Tangela Untangled
>Diglett & Dugtrio Unearthed
>Kangaskhan Baby Form
>Shellder Spiral Form
>Arbok's six different patterns
>Ivysaur's bipedal form
>Koffing's inverted face form
>The three pokemon that passed away in the burning tower and were resurrected by ho-oh (flareon, vaporeon, jolteon).