The Giovanni's Gyarados (5 / 132) card can be found in the Gym Challenge Unlimited set.
Recently sold 7 times and based on those sales is worth around £27.00.
Currently, there are 9 open listings for this card on ebay.
This card sells in the range of £10.48 to £43.52, making it quite volatile.
This Rare Holo card was illustrated by Ken Sugimori.