From Bulbapedia, the community-driven Pokémon encyclopedia.
Olivier (Japanese: オサバキ Osabaki) is a character who appears in Pedal to the Mettle! and Evolving Strategies!. He is a traveling referee who had been called by Reggie to preside over Ash and Paul's Full Battle.
He told Ash where the battle with Paul was going to take place, and also refereed their match. Olivier travels via hot air balloon, which also contains a screen, similar to the ones used in tournaments, such as the Pokémon League. He also hired Team Rocket—who were in disguise—to help him in updating the scoreboard.
He was seen in a flashback in Uncrushing Defeat!.