Chansey is card #76 of 123 in Mysterious Treasures (2007), a Common illustrated by Atsuko Nishida. At about $8.10 it is the #44 most valuable card in the set. In a Mysterious Treasures booster it turns up about once every 9 packs. It is one of 25 Chansey cards printed so far.
1999Base Set
2003Ruby & Sapphire
2005Unseen Forces
2007Mysterious Treasures
2010HeartGold & SoulSilver
2014Phantom Forces
2018Lost Thunder
2021Fusion Strike

















See the full Mysterious Treasures card list
An ungraded Chansey from Mysterious Treasures sells for about $8.10. A PSA 10 is worth more, roughly $64.80 by our estimate, and a PSA 9 around $22.68.
It is a Common, and it shows up about once every 9 Mysterious Treasures packs.
Atsuko Nishida drew the art for this card.
Yes, as a digital simulator. Holobrook lets you open Mysterious Treasures booster packs in your browser with the set's real pull rates and keep what you pull in a digital binder. No real cards, nothing to buy.