AttackPoison Buildup
Koga's Arbok is now Poisoned.

Arbok is Pokédex #024, generation 1 (Kanto). Koga's Arbok is a Stage 1 Grass Pokémon with 90 HP. The card lists level 44. The card says it evolves from Koga's Ekans. In this catalog that name is Ekans (#023).
Koga's Arbok sits at 25/132 in Gym Challenge, position 25 of 132. Before it is 24 Giovanni's Pinsir, and after it is 26 Koga's Muk. The set belongs to the Gym series. It was released on 16 October 2000. The printed size is 132, and the checklist is the same length. The listed rarity is Rare.
The attack Poison Buildup lists no damage number. The cost is Grass. Koga's Arbok is now Poisoned. Poison Power is another attack lists 20 damage. The cost is Grass, Grass. If Koga's Arbok is Poisoned, this attack's base damage is 40 instead of 20 and the Defending Pokémon is now Poisoned. Weakness is Psychic ×2. Retreat cost is 2.
Arbok (#024) has 19 other cards in the catalog. Those other cards are in 15 sets. The other printings with a release date run from 1999 to 2025. The earliest other card is Arbok 31/62 in Fossil (1999). That card is named Arbok, while this one is Koga's Arbok. That card lists 60 HP, and this one lists 90 HP. The rarity there is Uncommon, and here it is Rare. 17 other cards of Arbok 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. Arbok 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.
Koga's Arbok is now Poisoned.
If Koga's Arbok is Poisoned, this attack's base damage is 40 instead of 20 and the Defending Pokémon is now Poisoned.
Gym Challenge, in the Gym series. It was released on 16 October 2000. The printed size is 132.
25/132. It is entry 25 of 132 in this checklist.
Ken Sugimori. The catalog lists 1,112 other cards with that illustrator.
Rare.
Arbok #024, generation 1 (Kanto).
Poison Buildup and Poison Power (20).