Disclaimer below for comedic effect

The ridiculously overpowered villain smirked at Goku over the shattered battlefield. "I see that you are in fact not to be trifled with. But you have not yet faced my true perfect ultimate form!" He growled as a series of neon colors engulfed his body, transforming him into the true perfect ultimate form.

Goku stared back, his eyes icy under oddly colored hair. "In that case, I must use my own overpowered but not yet revealed finishing move."

The unnamed villain gasped. "You-you don't mean, not that-"

Goku nodded. "Yes. THAT attack." He draw his hands to his side and began gathering energy. "Ka..."

Across the island, the villain quickly scanned his options and came to the only possible conclusion. Going to lose, because we're both in our actual ultimate forms (for now) and he's the good guy and using his finishing move. Damn.

"..ME...HA..." the building attack's vocalization continued from Goku's location.

It's too bad that I'm not allowed to dodge these ultimate finishing moves. Stupid rules.

Goku's yelled the finish of his overpowered finishing attack as the energy blast took shape. "...ME...HA HA!"

The villain's last thoughts as the blast of energy rolled over him were regretful. The indignity-killed by a stupid energy blast shaped like a submarine.

Notes:

The USS Kamehameha (emphasis on the second and fourth syllables) was commissioned a ballistic missile submarine in 1965 and is (or was before it was decommissioned) owned by the US Navy/Government.

Dragonball Z is owned by someone who isn't me.