Diesector versus Final Destiny in Season 5. Final Destiny was a rookie robot that was, in the builder's words, "designed to defeat Diesector and Toro", who were the two bots to watch in the Superheavyweight division. Diesector's standard weapons (a pair of clamping jaws and two hammers) didn't look like they'd be effective against FD's design (very low, giant spinning bar, similar to Hazard). Then when the fight starts we see that Diesector's team had actually removed its hammers and added two pipes to its jaws. The pipes slide under Final Destiny effortlessly and lift its own armor into the path of its blade. Final Destiny proceeds to rip its own armor off because it has no other way to fight and is helpless against Diesectors repeated lifts. The fight ends with Final Destiny spinning out of control and landing on its head as Diesector "yawns" at the effortless victory, surviving the "Diesector Killer" without a single injury.
Made especially awesome by the pre-fight interviews. Diesector's driver, Donald Hutson, says that he will "remove off [Final Destiny's] clovers, one leaf at a time." At the time, it seems like some obscure, luck-related metaphor, but once the fight begins, he proceeds to do exactly that.
Ziggo vs. Scrap Daddy. You can go ahead and guess which robot lives up to its name by the end of this match.
Blendo. First, the men who would become the Mythbusters designed this death machine. Second was that it was too hardcore to compete in Battlebots most of the time. It was so powerful that in early appearances it would damage the arena and send bits of its opponents and itself over the arena walls. Then, when it competed in the arena for the television show, it would frequently tear itself to pieces from its own power. If ever there were a robot that took to the arena like a Viking berserker, it was Blendo.