From Bulbapedia, the community-driven Pokémon encyclopedia.
Miyuki Sawashiro (沢城みゆき Sawashiro Miyuki, born June 2, 1985 in Tokyo), is a Japanese seiyū for the Pokémon anime. She starting out voicing Marley and various characters of the day. Her most prominent role was of Olivia in the Sun and Moon series.
In the anime
In the animated trailers