Saitama + Saitama = Destruction

Despite an output of dozens of punches per second, Saitama found that his doppelganger was matching his every move, with the two men striking each and every blow in unison and countering it with the exact same hit. Their fists colliding into each other with enough force to rip apart a planet, the duo continued falling towards the large, icy world below them and sustained their exchange even as their bodies were engulfed in red as they started burning up in the atmosphere.

"HAHA fool, you're falling right towards the trap that I set for you down there on the surface!" the bald clown laughed.

"Huh? Where?" alt-Saitama replied as he stopped his attack and turned his head to look.

"Idiot," Saitama smirked as he clenched his bare fist and threw it at his lookalike. "Conquerors Series: Conquest Punch!!"

His hand making contact with alt-Saitama's chest alone exerted more energy than 10 hydrogen bombs going off at once with the impact, but the total power of the attack itself was hundreds of times greater. A giant shockwave blew a hole in the planet's atmosphere as the crushing punch propelled the yellow-suited man into the surface at the speed of light.

Grinning, the bald clown watched as the planet fractured and a crater the size of Earth itself formed from the tremendous impact of alt-Saitama hitting it, where trillions upon trillions of tons of rock were blasted into outer space and the entire world was knocked out of its orbit. His ears perking up as he sensed an attack heading his way, Saitama raised his arms to block a wave of consecutive serious punches as they flew at him from the point of impact.

"I-I think you broke one of my ribs!" the alternative caped baldy exclaimed with a smile of his own as he jumped from the 80,000 foot hole continued his sustained barrage of punches. "I forgot how thrilling pain could be!"

"Right? Though if you have any hope of killing me, you'd better knock it off with these baby attacks!" the magenta-caped man teased as he shook off the many city-destroying hits as he stretched out his hand to snatch his doppelganger's own white cape in midair. "I know its something that we're not used to, but you're going to need to really to start seeing me as a serious threat!"

Dragging his foe into a high-G spin, Saitama built up a ton of momentum before releasing his hold on the cape and letting alt-Saitama shoot back into the crater that he'd just made, where he bounced several times against the solid rock that had been kicked up from the impact before coming to rest by some newly-formed mountains.

Finally touching down on the now-damaged planet's surface, the bald villain brushed off his suit as he cracked his knuckles in preparation for another attack. It was his turn to be on the defensive, however, as chunks of rock the size of battleships began to fly at him from the mountain range, where an area the size of Manhattan was rained down upon by falling snow and stone as they slowly fell upon the grey-suited man.

"Really? Buddy, I'm not one of the small-fry monsters that we used to fight," Saitama snickered as he threw a series of simple punches to easily demolish the mini mountains that had been thrown at him. "If you really want to damage me, then-"

"-I have to think like you, right?" alt-Saitama asked as he was suddenly underneath the bald clown's feet, having tunneled out of a hole in the ground. "Killer Move: Actually Serious Punch!"

The red-gloved man delivered a devastating uppercut to his villainous counterpart, which shot his opponent into the skies with enough velocity to escape the planet's gravity, where the force of the hit buckled the surface of the area around them.

Rubbing his aching jaw, Saitama giggled as he was shot thousands of feet into the air, where he reared back his arm and devoted himself to another full-powered punch as his lookalike jumped into the air after him with an attack of his own ready. Delivering their punches at the same time, another catastrophic shockwave blew a second hole in the planet's atmosphere as the attacks connected, where the two Saitama's stared into each other's wide eyes with amusement.

"I'm you, remember? Evil or not, I already think like you!" the white-caped man smiled as their blows had harmlessly negated each other.

"Maybe in some ways, but I've done things that that your naïve self could never dream of!" Saitama replied as he grabbed his foe's wrist and bent it backwards with an audible crack. Despite the shudder-worthy sound of a bone snapping, alt-Saitama merely stared at his duplicate with annoyance.

"You say I don't know evil but surely in your reality, you've fought bad guys as evil as I did! What make you think that I don't understand monsters first hand?" the yellow-clad hero asked as he snatched his opponent's bald head. "Killer Move: Bowling Strike!"

Forcing the evil version of himself into a spin, alt-Saitama threw the man via his round head with such force that he spun towards the planet and ricocheted off its surface like a living musket ball. Laughing as if he'd just gotten off of an amusement park ride, the bald clown rose to his feet after easily recovering from his ride down from the stratosphere and let out a loud grunt as he put his back into his next attack.

"Conquerors Series: Armada Wave!" Saitama yelled as he threw a slow succession of several punches as his opponent descended in front of him.

Trying to change his direction in midair, the alternate caped baldy managed to dodge most the devastating blows, but of course, the only person could match his speed was himself. Tasting blood as he took a direct hit from one of the full powered punches, alt-Saitama grinned again as he wiped a speck of red from his lip before vanishing as he blitzed towards his opponent.

"Conquerors Series? You have some cool attack names, I'm sort of jealous," the yellow-suited man goaded as he circled his opponent faster than the human eye could detect. "Well, we have all day, I guess I'll give it a try. Liberator Series: Punch of Liberation!!"

"HAHAHA bring it, me!" the bald clown laughed as his doppelganger charged and punched him in the side of the head.

Saitama barreled into the ground and tore yet another devastating hole in the planet's crust as he skimmed the molten core and popped out nearly halfway around the world. Now 120,000 miles away from his foe, the caped baldy clapped his hands as he again brushed off his grey suit, the taste of blood now entering his own mouth as he reveled in the small, albeit, superficial damage that he'd taken so far from his lookalike.

As exciting as it was, he had no idea just how long the road ahead was.