From Bulbapedia, the community-driven Pokémon encyclopedia.
Ichiishi's lone illustration
Sayuri Ichiishi (Japanese: 一石小百合) was the lead anime character designer for the Pokémon anime and currently works for OLM Incorporated.
In addition to this, she worked as an animation director in the first episode and Mewtwo Returns, and also as an illustrator for the Pokémon Trading Card Game. The single card that she illustrated, Pichu Bros., was a promotion for Camp Pikachu, a Pikachu short for which she had worked as the character designer.
Although she now no longer works for the main anime, she does help with the creation of each Pokémon movie.