Yu-Gi-Oh! Episode 21: The Fiend Dragon B. Skull Dragon
Episode 21 of 224 of Yu-Gi-Oh!, aired September 12, 2000, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Yugi and Joey each unleash their strongest monster, the Summoned Skull and the Red Eyes Black Dragon, but their strength pales in comparison to the tremendous power of the Gate Guardian. Nevertheless, Yugi and Joey battle on, knowing that even if they defeat the brothers they must still solve the riddle of the doors or remain underground forever.