It exists in several finishes (Normal, 1st edition). Each one has its own price; the average above is for the regular version.
Artwork by Ken Sugimori. Some collectors chase every card by the same artist: how to start (in Spanish).
Abilities
Energy Drain Pokemon Power
If an opponent's attack does damage to Koga's Muk (even if Koga's Muk is Knocked Out), flip a coin. If heads and if it has any, choose 1 Energy card attached to the attacking Pokémon and discard it. This power can't be used if Koga's Muk is already Asleep, Confused, or Paralyzed when your opponent attacks.