The Slowbro EX (26 / 108) card can be found in the Evolutions set.
Recently sold 8 times and based on those sales is worth around £2.42.
Currently, there are 8 open listings for this card on ebay.
This card sells in the range of £0.84 to £4.00, making it very stable.
This Rare Holo Ex card was illustrated by Ayaka Yoshida.
The fact that it is a EX card makes it one of the more valuable cards.