AttackPoltergeist
Look at your opponent's hand. This attack does 40 damage plus 10 more damage for each Trainer card in your opponent's hand.

Gengar is Pokédex #094, generation 1 (Kanto). Gengar ex is a Stage 2 ex Psychic Pokémon with 150 HP. The card says it evolves from Haunter. In this catalog that name is Haunter (#093).
Gengar ex sits at 108/112 in FireRed & LeafGreen, position 108 of 116. Before it is 107 Electrode ex, and after it is 109 Gyarados ex. The set belongs to the EX series. It was released on September 1, 2004. The printed size is 112. This checklist is longer, at 116 cards. The listed rarity is Rare Holo EX.
The attack Poltergeist lists 40+ damage. The cost is Psychic, Colorless. Look at your opponent's hand. This attack does 40 damage plus 10 more damage for each Trainer card in your opponent's hand. Prize Count is another attack lists 60+ damage. The cost is Psychic, Psychic, Colorless. If you have more Prize cards left than your opponent, this attack does 60 damage plus 40 more damage. Weakness is Psychic ×2 and Darkness ×2. Resistance is Fighting -30 and Colorless -30. Retreat cost is 2. The card text says: When Pokémon-ex has been Knocked Out, your opponent takes 2 Prize cards.
Gengar (#094) has 52 other cards in the catalog. Those other cards are in 34 sets. The other printings with a release date run from 1999 to 2026. The earliest other card is Gengar 5/62 in Fossil (1999). That card is named Gengar, while this one is Gengar ex. That card lists 80 HP, and this one lists 150 HP. The rarity there is Rare Holo, and here it is Rare Holo EX. Keiji Kinebuchi illustrated that card, and Mitsuhiro Arita illustrated this one. Retreat cost there is 1, and here it is 2. 52 other cards of Gengar list a different HP.
The illustrator line reads Mitsuhiro Arita. I count 721 other cards in the catalog with that illustrator.
FireRed & LeafGreen set binder is where a full FireRed & LeafGreen set goes. This card fills one slot there. A generation binder holds one card of each species. Gengar can fill a slot in Generation 1 binder (Kanto). Themed lists that include this exact card are Gengar and the Gastly line and Mitsuhiro Arita cards. I still need this card.
Look at your opponent's hand. This attack does 40 damage plus 10 more damage for each Trainer card in your opponent's hand.
If you have more Prize cards left than your opponent, this attack does 60 damage plus 40 more damage.
When Pokémon-ex has been Knocked Out, your opponent takes 2 Prize cards.
FireRed & LeafGreen, in the EX series. It was released on September 1, 2004. The printed size is 112.
108/112. It is entry 108 of 116 in this checklist.
Mitsuhiro Arita. The catalog lists 721 other cards with that illustrator.
Rare Holo EX.
Gengar #094, generation 1 (Kanto).
Poltergeist (40+) and Prize Count (60+).