The Blissey (H6) card can be found in the Aquapolis set.
Recently sold 4 times and based on those sales is worth around £25.02.
Currently, there are 3 open listings for this card on ebay.
This card sells in the range of £15.04 to £35.00, making it quite stable.
This Rare Holo card was illustrated by Naoyo Kimura.