The Brock's Ninetales (3 / 132) card can be found in the Gym Challenge Unlimited set.
Recently sold 10 times and based on those sales is worth around £27.32.
Currently, there are 18 open listings for this card on ebay.
This card sells in the range of £18.99 to £35.65, making it quite stable.
This Rare Holo card was illustrated by Ken Sugimori.