Hachihyaku is an antagonist of the Dragonball Z OVA "The Plan to Eradicate the Saiyans". It first appears as Dr. Raiichi's supercomputer, but later materializes into a powerful fighter after absorbing the pure hatred of Dr. Raiichi. Afterward, the supercomputer appeared to be too powerful for the Z Fighters to handle. Luckily, after about 15 minutes of a rather one-sided fight, Goku learns of Hachihyaku's weakness; Hatchihyaku only fired his energy blast after 15 seconds. Knowing this, Goku and the others begin powering up their strongest blasts, and fire at the count of 15. This proves to be more than enough to fully destroy Hachihyaku.
Hachihyaku is said by Goku to be stronger than Broly. However, it should be noted that this was stated prior to Broly: Second Coming and Broly's strength may have increased significantly by that time. But that statement in itself leaves another plothole as weaker Adult Gohan and Goten are able to defeat Broly own thier own with coaching from Ghost Goku.