Dragon Ball Z Episode 120: Another Super Saiyan?
Episode 120 of 291 of Dragon Ball Z, aired December 11, 1991, 25 minutes. Available with English subtitles and dub where released.
Episode summary
As Frieza and King Cold prepare to strike, a mysterious young man armed with a sword comes out of nowhere and challenges them to fight. It looks like this boy has made a grave mistake, or maybe ...it's the other way around.