From Bulbapedia, the community-driven Pokémon encyclopedia.
Contest announcers are people who comment on the Pokémon Contests and Super Contests. They also announce the start of the Contests.
In the games
Generation III games
In Pokémon Ruby, Sapphire, and Emerald, they appear in the Contest Halls to announce the start of the rounds. They also announce the winner and present them with their Ribbon.
Generation IV games
In Pokémon Diamond, Pearl, and Platinum, the announcer is Dexter, who is also a judge.
In the anime
In Japanese, the three anime announcers share アン an on their names. In English, they also share an in their names.