Pokémon is one of the most popular franchises of all time, spanning video games, anime and beyond as it continues to reach a global audience. To achieve these once-unfathomable levels of success, Pokémon has had to continually deliver on fresh additions for over twenty years now, and the franchise now sits at nine generations and over 1000 species on its roster. Every species is different in some way, from stats and design, to personality and types.
Source：https://www.cbr.com/dark-type-pokemon-weakness/
