From Bulbapedia, the community-driven Pokémon encyclopedia.
5ban Graphics is a group of artists who have illustrated many cards for the Pokémon Trading Card Game from Black and White onward. The group has designed many Trainer Cards, as well as many Full Art cards and Pokémon cards for the Black and White, XY, and Sun & Moon TCG Series.
An example of 5ban Graphics' work
Little is known about the group. In 2012, a brief interview about the creation of card artwork was posted on the Creatures, Inc. PTCG blog in which they state they like to make the Pokémon look 3D along with exemplifying the best qualities of the Pokémon when possible so they stand out on their own.
For a list of cards illustrated by 5ban Graphics, go here.
PTCG Blog ポケモンカードができるまで ～イラスト編～ (Japanese, archived)