Pokémon as a franchise is not known for particularly difficult mainline games. Even with the introduction of open-world games in Scarlet and Violet, wherein players can easily challenge trainers at a higher level at any time, the games remain straightforward to complete. For long-time players the explanation is simple—once the basic strategies of the game are grasped, any trainer can be a breeze. To this, the Pokémon community has developed a non-official rule set to increase the challenge: the Nuzlocke Challenge.
Source：https://www.cbr.com/pokemon-every-generation-nuzlocke-tips-tricks/
