The Dialga (4 / 100) card can be found in the Majestic Dawn set.
Recently sold 4 times and based on those sales is worth around £6.54.
Currently, there are 2 open listings for this card on ebay.
This card sells in the range of £3.95 to £9.13, making it stable.
This Rare Holo card was illustrated by Masakazu Fukuda.