As the Pokemon Company and GameFreak continue to add more and more Pokemon into the Pokemon Universe, less and less Pokemon seem to be available, compared to the growing National Pokedex, within each and every game. (Though the National Pokedex again fails to make a return within The Alola Region.) And actually, this is more truthful than you know within the Seventh Generation. You see, if a Pokemon isn't found within the entire Alola Pokedex, odds are it isn't found within the game. There are more than three hundred older generation Pokemon that cannot be found during your journey and even afterwards.
This means that more than ever before, players will have to rely heavily on Transfer Pokemon through Poke Bank, the only known way to get all there Pokemon from older generations. Even this method could prove not enough to obtain every last Pokemon, causing players to have trade for any remaining Pokemon they couldn't find within the game or by transferring. There are now over eight hundred Pokemon to obtain, the largest known sum to date within the World of Pokemon.