The Pikachu (SWSH020) card can be found in the Swsh Black Star Promos set.
Recently sold 8 times and based on those sales is worth around £31.75.
Currently, there are 12 open listings for this card on ebay.
This card sells in the range of £25.38 to £38.12, making it quite stable.
This Promo card was illustrated by Hideki Ishikawa.