Striking Golduck (Japanese: VSゴルダックVS Golduck) is the 77th chapter of the Pokémon Adventures manga, and the 37th chapter of the Yellow arc.
Plot
Spoiler warning: this article may contain major plot or ending details.
On Cerise Island, Blue is walking with Koga. They find themselves lost in the maze created by Agatha's Arbok. Koga finds the broken tail of his own Arbok that got cut by Agatha's Pokémon earlier. They immediately figure out that they have been going in circles and try to figure out a way to get out.
Koga starts to faint, and says it is not normal for him to lose so much strength simply from a Leech Life from Golbat. He thinks that something else is draining away his energy, and Blue tells him to take it easy. Blue hears a sound from behind and looks down and notices his own shadow lengthening; he releases his Golduck to get ready. Koga calls his Koffing, but Gengar shoots from Golduck's shadow without warning and knocks down both Golduck and Koffing.
Blue sends out his Charizard, Scyther, and Ninetales to attack Gengar, but it escapes into Blue's shadow and attacks Blue's Pokémon. Blue realizes that the more Pokémon he sends out, the more shadows Gengar can escape in, so he calls back his fainted Pokémon. Koga discovers his theory was right, that Gengar is stealing energy from himself, and Blue tells him to stay where he's sitting. Blue sends out his Porygon and makes it use Conversion to make Gengar's physical attacks useless. However that doesn't stop Gengar from attacking Blue, and he wonders if there's a way to bring Gengar out of the shadows.