Boundaries Crossed is a set in the Black & White series. It was released on 7 November 2012. The printed size is 149. This checklist is longer, at 153 cards. Ditto is 108/149, in position 108 of 153 on this checklist. Before it is 107 Farfetch'd, and after it is 109 Snorlax. The listed rarity is Rare Holo.
Ditto is a Basic Colorless Pokémon with 70 HP. In the Pokédex this is Ditto (#132), generation 1 (Kanto).
HiRON illustrated this card. The same name is on 12 other cards in the catalog.
Ditto (#132) has 31 other cards in the catalog. Those other cards are in 19 sets. The other printings with a release date run from 1999 to 2026. The earliest other card is Ditto 3/62 in Fossil (1999). That card lists 50 HP, and this one lists 70 HP. Both list the rarity Rare Holo. Keiji Kinebuchi illustrated that card, and HiRON illustrated this one. 26 other cards of Ditto list a different HP.
Transform is listed as Ability. During your turn (before your attack), you may put a Basic Pokémon from your hand on top of this Pokémon. (This does not count as playing that Pokémon or evolving.) This Pokémon is now that Pokémon. (Any cards attached to this Pokémon, damage counters, Special Conditions, turns in play, and any other effects remain on the new Pokémon.) Weakness is Fighting ×2. Retreat cost is 1. The flavor text reads "It can reconstitute its entire cellular structure to change into what it sees, but it returns to normal when it relaxes."
I keep a set binder for Boundaries Crossed, meant to hold every card of that set. This card is one slot in the Boundaries Crossed set binder. A generation binder holds one card of each species. Ditto can fill a slot in Generation 1 binder (Kanto). I still need this card.