AttackSmokescreen
If the Defending Pokémon tries to attack during your opponent's next turn, your opponent flips a coin. If tails, that attack does nothing.

Gym Challenge is a set in the Gym series. It was released on October 16, 2000. The printed size is 132, and the checklist is the same length. Koga's Koffing is 48/132, in position 48 of 132 on this checklist. Before it is 47 Koga's Kakuna, and after it is 49 Koga's Pidgey. The listed rarity is Uncommon.
Koga's Koffing is a Basic Grass Pokémon with 50 HP. The card lists level 15. In the Pokédex this is Koffing (#109), generation 1 (Kanto). The card lists Weezing, Weezing (#110) under evolves to.
Ken Sugimori illustrated this card. The same name is on 1,112 other cards in the catalog.
Koffing (#109) has 28 other cards in the catalog. Those other cards are in 26 sets. The other printings with a release date run from 1999 to 2025. The earliest other card is Koffing 51/102 in Base (1999). That card is named Koffing, while this one is Koga's Koffing. Both list 50 HP. The rarity there is Common, and here it is Uncommon. Mitsuhiro Arita illustrated that card, and Ken Sugimori illustrated this one. 20 other cards of Koffing list a different HP.
The attack Smokescreen lists 10 damage. The cost is Grass. If the Defending Pokémon tries to attack during your opponent's next turn, your opponent flips a coin. If tails, that attack does nothing. Obscuring Gas is another attack lists 30 damage. The cost is Grass, Colorless. Flip a coin. If heads, shuffle Koga's Koffing and all cards attached to it into your deck (after doing damage). Weakness is Psychic ×2. Retreat cost is 1.
I keep a set binder for Gym Challenge, meant to hold every card of that set. This card is one slot in the Gym Challenge set binder. A generation binder holds one card of each species. Koffing can fill a slot in Generation 1 binder (Kanto). Themed lists that include this exact card are Trainer's Pokémon and Kanto Gym Leaders and their Pokémon. I still need this card.
If the Defending Pokémon tries to attack during your opponent's next turn, your opponent flips a coin. If tails, that attack does nothing.
Flip a coin. If heads, shuffle Koga's Koffing and all cards attached to it into your deck (after doing damage).
Gym Challenge, in the Gym series. It was released on October 16, 2000. The printed size is 132.
48/132. It is entry 48 of 132 in this checklist.
Ken Sugimori. The catalog lists 1,112 other cards with that illustrator.
Uncommon.
Koffing #109, generation 1 (Kanto).
Smokescreen (10) and Obscuring Gas (30).