9. Diploma - Pokemon
The whole driving mission behind all things Pokemon - "gotta catch 'em all" - admittedly puts it in a weird spot when it comes to rewards and unlockables. "Catching 'em all" includes getting the secret and legendary Pokemon, so the reward is the task itself; the journey, not the destination.
However, we have to believe developer Game Freak can do better than THIS.
For successfully completing your Pokedex, your reward is a diploma. Maybe back in the Stone Age when there were only 151 Pokemon and you could print this bad boy out on your GameBoy printer to show your friends at recess, it was kinda sorta neat.
But as that number grew with every new entry - hitting 400 with the most recent releases, Scarlet and Violet - a plain in-game certificate of completion feels less and less rewarding.
The worst part about the diploma is the profound sense that you and your accomplishments are not particularly special or unique in this world. How many other Pokemon trainers have diplomas? Is it like finishing high school or something? Does it unlock anything??