In the main series, each game's single-player mode requires the Trainer to raise a team of Pokémon to defeat many non-player character (NPC) Trainers and their Pokémon. Each game lays out a somewhat linear path through a specific region of the "Pokémon" world for the Trainer to journey through, completing events and battling opponents along the way (including foiling the plans of an 'evil' team of Pokémon Trainers who serve as antagonists to the player). Excluding "Pokémon Sun" and "Moon" and "Pokémon Ultra Sun" and "Ultra Moon", the games feature eight powerful Trainers, referred to as Gym Leaders, that the Trainer must defeat in order to progress. As a reward, the Trainer receives a Gym Badge, and once all eight badges are collected, the Trainer is eligible to challenge the region's Pokémon League, where four talented trainers (referred to collectively as the "Elite Four") challenge the Trainer to four Pokémon battles in succession. If the trainer can overcome this gauntlet, they must challenge the Regional Champion, the master Trainer who had previously defeated the Elite Four. Any Trainer who wins this last battle becomes the new champion.