Alder/Manga/PA

Alder first appears in 's imagination when he voices his desire to defeat them. Alder debuts in person at Nimbasa City, which he travels to on the top of his. Upon arriving, he meets up with Marshal, who was waiting there. They go to meet the Mayor of Nimbasa City, who called them there to help test the newly-made Battle Subway. While they wait for the mayor to arrive, Alder battles Marshal in a test run and ends up winning. Annoyed that the mayor has still not arrived, Alder takes a break and plays with the wild Pokémon outside. He returns from playing a day later, and gets annoyed that the mayor had come and left while he was away. When and  tease him for slacking off, Alder claims that he was not playing, but going on a spiritual journey. He asks White why she decided to also test the Battle Subway, to which she replies that she's doing this to understand why her Pokémon had left her to pursue battling. Alder admits that White's story is better, much to Black's annoyance.

Sometime later, Alder and Marshal walk around. Marshal tries to convince his master to not give up his title as Pokémon League Champion, but Alder refuses. They are interrupted by Team Plasma's King,, who insults Alder and the 🇺🇳 by calling them stupid. N challenges Alder to a Double Battle as a part of his plan to keep humans and Pokémon separated. The battle gets the attention of Black, White, and Iris, who all see that Alder has already lost three Pokémon while N still has three. Alder manages to defeat N's, but is defeated by a combination of and Gigi, all without N even needing to use his.

After his defeat, Alder disappeared, and left the Pokémon League to be handled by the Elite Four. Team Plasma uses N's victory over Alder to justify their goal, which only increased the amount of released Pokémon and lowered the number of Pokémon League spectators.