AttackGiant Growth
Flip a coin. If heads, Koga's Ditto's maximum HP is now 80 and Koga's Ditto's Pound attack's base damage is 30 instead of 10. (Benching Koga's Ditto ends this effect.)

Ditto is Pokédex #132, generation 1 (Kanto). Koga's Ditto is a Basic Colorless Pokémon with 40 HP. The card lists level 12.
Koga's Ditto sits at 10/132 in Gym Challenge, position 10 of 132. Before it is 9 Koga's Beedrill, and after it is 11 Lt. Surge's Raichu. The set belongs to the Gym series. It was released on October 16, 2000. The printed size is 132, and the checklist is the same length. The listed rarity is Rare Holo.
The attack Giant Growth lists no damage number. The cost is Colorless. Flip a coin. If heads, Koga's Ditto's maximum HP is now 80 and Koga's Ditto's Pound attack's base damage is 30 instead of 10. (Benching Koga's Ditto ends this effect.) Pound is another attack lists 10 damage. The cost is Colorless. Weakness is Fighting ×2. Resistance is Psychic -30. Retreat cost is 1.
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 is named Ditto, while this one is Koga's Ditto. That card lists 50 HP, and this one lists 40 HP. Both list the rarity Rare Holo. Keiji Kinebuchi illustrated that card, and Ken Sugimori illustrated this one. 29 other cards of Ditto list a different HP.
The illustrator line reads Ken Sugimori. I count 1,112 other cards in the catalog with that illustrator.
Gym Challenge set binder is where a full Gym Challenge set goes. This card fills one slot there. A generation binder holds one card of each species. Ditto can fill a slot in Generation 1 binder (Kanto). Themed lists that include this exact card are Trainer's Pokémon, All Ditto cards, and Kanto Gym Leaders and their Pokémon. I still need this card.
Flip a coin. If heads, Koga's Ditto's maximum HP is now 80 and Koga's Ditto's Pound attack's base damage is 30 instead of 10. (Benching Koga's Ditto ends this effect.)
Gym Challenge, in the Gym series. It was released on October 16, 2000. The printed size is 132.
10/132. It is entry 10 of 132 in this checklist.
Ken Sugimori. The catalog lists 1,112 other cards with that illustrator.
Rare Holo.
Ditto #132, generation 1 (Kanto).
Giant Growth and Pound (10).