In-game events: The game usually provides the player with one or more Master Balls as event items during their journey. For example, in some games, you may receive a Master Ball for achieving certain milestones or defeating specific trainers.
Certain locations: Master Balls can sometimes be found hidden in secret or remote locations within the game world. This may require exploration and puzzle-solving.
Rare items: Occasionally, a Master Ball can be bought as a rare item using in-game currency or from specific shops. The availability and cost of a Master Ball in such cases may vary.
In-game trades: Certain characters or NPCs may offer Master Balls in exchange for specific items or Pokémon. This might depend on your progress in the game.
Special gifts or rewards: Players can sometimes receive a Master Ball as a reward for participating in special events, competitions, or challenges within the game.
The distribution of Master Balls can vary across different Pokémon games, so the specific details may differ depending on the title you are playing. Make sure to explore thoroughly, keep an eye out for event rewards, and check for special shop items to increase your chances of obtaining a Master Ball.