Pokemon uses the same psychological techniques as casinos and lootboxes to manipulate players into putting up with the series' tedious, boring gameplay. Pokemon requires no skill on the part of the player, but rather leans heavily on a randomness-reward system to give players a cheap dopamine hit.

>"We know that the dopamine system, which is targeted by drugs of abuse, is [...] very interested in unpredictable rewards. Dopamine cells are most active when there is maximum uncertainty, and the dopamine system responds more to an uncertain reward than the same reward delivered on a predictable basis."

https://www.pcgamer.com/behind-the-addictive-psychology-and-seductive-art-of-loot-boxes/

RNG is employed in almost all aspects of Pokemon (encountering Pokemon, capturing Pokemon, attack effectiveness) to keep a sense of randomness at the forefront of the experience. Pokemon isn't as insidious as casinos and lootboxes, as it doesn't require for the player to pay real world money to 'gamble', beyond the initial price of the game, but it still uses RNG as a substitute for actual, enjoyable gameplay.