AttackPrehistoric Water
If your opponent has any evolved Pokémon in play, choose 1 of them and flip a coin. If heads, your opponent takes the highest Stage Evolution card on that Pokémon and shuffles it into his or her deck.

Omastar is Pokédex #139, generation 1 (Kanto). Dark Omastar is a Stage 2 Water Pokémon with 70 HP. The card lists level 33. The card says it evolves from Dark Omanyte. In this catalog that name is Omanyte (#138).
Dark Omastar sits at 19/105 in Neo Destiny, position 19 of 113. Before it is 18 Dark Magcargo, and after it is 20 Dark Slowking. The set belongs to the Neo series. It was released on February 28, 2002. The printed size is 105. This checklist is longer, at 113 cards. The listed rarity is Rare.
The attack Prehistoric Water lists no damage number. The cost is Water. If your opponent has any evolved Pokémon in play, choose 1 of them and flip a coin. If heads, your opponent takes the highest Stage Evolution card on that Pokémon and shuffles it into his or her deck. Dark Tentacle is another attack lists 30 damage. The cost is Water, Colorless. During your opponent's next turn, the Defending Pokémon can't evolve except from effects of attacks or Pokémon Powers. (Benching that Pokémon ends this effect.) Weakness is Grass ×2. Retreat cost is 2. The flavor text reads "Nothing can escape once wrapped in its tentacles, which it uses for self-defense as well as to catch food."
Omastar (#139) has 16 other cards in the catalog. Those other cards are in 14 sets. The other printings with a release date run from 1999 to 2023. The earliest other card is Omastar 40/62 in Fossil (1999). That card is named Omastar, while this one is Dark Omastar. Both list 70 HP. The rarity there is Uncommon, and here it is Rare. Ken Sugimori illustrated that card, and Tomokazu Komiya illustrated this one. Retreat cost there is 1, and here it is 2. 14 other cards of Omastar list a different HP.
The illustrator line reads Tomokazu Komiya. I count 248 other cards in the catalog with that illustrator.
Neo Destiny set binder is where a full Neo Destiny set goes. This card fills one slot there. A generation binder holds one card of each species. Omastar can fill a slot in Generation 1 binder (Kanto). Themed lists that include this exact card are Team Rocket cards, Fossil Pokémon, and Tomokazu Komiya cards. I still need this card.
If your opponent has any evolved Pokémon in play, choose 1 of them and flip a coin. If heads, your opponent takes the highest Stage Evolution card on that Pokémon and shuffles it into his or her deck.
During your opponent's next turn, the Defending Pokémon can't evolve except from effects of attacks or Pokémon Powers. (Benching that Pokémon ends this effect.)
Nothing can escape once wrapped in its tentacles, which it uses for self-defense as well as to catch food.
Neo Destiny, in the Neo series. It was released on February 28, 2002. The printed size is 105.
19/105. It is entry 19 of 113 in this checklist.
Tomokazu Komiya. The catalog lists 248 other cards with that illustrator.
Rare.
Omastar #139, generation 1 (Kanto).
Prehistoric Water and Dark Tentacle (30).