Max.

Max is the youngest mainline traveler the show has ever had: seven years old when he debuts in AG001, eight or nine by the time he leaves in AG192. The legal trainer age in-universe is ten, so Max never owns a Pokémon during his run. He compensates by being the cast's walking encyclopedia: any time a wild Pokémon appears, Max recites stats and habits before May or Ash even ask. Functions as the audience's point-of-entry character for kids who weren't quite old enough to imagine being Ash.

His informal bonds across the arc include Ralts (which he saves from a snowstorm and which the show pointedly never lets him capture, since he's too young), Jirachi (during the Wish Maker film tie-in), and Manaphy (during the Pokémon Ranger and the Temple of the Sea film tie-in). He returns home in AG192 to wait for his own tenth birthday; the show implies he'll begin his journey by touring every Hoenn Gym Leader, but a Max-led spinoff never materialized.