While he is stunned, Batman can get close enough to One-Punch Man to shoot, stab, inject, burn, bomb or do whatever is necessary to take him out. Batman would not have much time, but then again he would not need much time to win a fight using planning and preparation.
Given this premise, in a straightforward one-on-one physical battle, Saitama, aka One-Punch Man, would likely emerge as the victor, as his power is portrayed as limitless and invincible.
Zeno from Dragon Ball Super couldn't just defeat Saitama but could put an end to everyone in the One Punch Man universe. He is the god of the multiverse and is so strong that he can wipe out the entire universe with a single thought.
In a battle against Hulk, every little bit counts. Saitama having this ability provides him a slight edge, as he effectively has a source of projectile attacks that he can use at a distance.
Even if Goku was able to use his highest form of power, Saitama's one-punch certainty means a fight wouldn't last for long. If we are to take Saitama's power and accuracy at face value, it almost doesn't matter who his opponent is — he would win outright.
Shonen Jump heroes are generally known for their ridiculous strength; however, One-Punch Man's Saitama is on a completely different level. Renowned for being able to end almost any fight in one punch, he just might be able to defeat Naruto — or any other shonen protagonist — in a one-on-one fight.
Beerus, no question. Saitama's best feats (getting kicked to the moon and jumping back to earth, splitting a life wiping energy beam, destroying a giant meteor etc) would barely place him at Namek Saga levels by DB standards.
The battle between Saitama and Thanos was intense and destructive, but ultimately, Saitama's immense strength and speed proved to be too much for even the all-powerful Thanos with all six Infinity Stones.
Saitama defeats his ghost in one hit. Genos tries to comfort Saitama by telling him his opponent was himself from yesterday, but to his shock, he sees Saitama defeated his ghost in a single punch.
Which means he could literally overcome Gojo's limitless if he wanted to, since his own strength is also limitless. The only excuse these biased Gojo fans have is Gojo's limitless, and without that, Saitama far outclasses him in every area by a LANDSLIDE. He could easily speedblitz Gojo.
Garou's Gamma Ray Burst (which is said to be the most powerful and destructive natural phenomenon in the universe) and nuclear explosions had all proved ineffective against Saitama even though they both possessed an amount of radiation that would be very fatal to normal humans.
Batman is also a caped martial artist hero, but even he can't beat Saitama at his own game. He would struggle against the Deep Sea King or the alien warlord Boros. By contrast, Saitama could beat any of Batman's enemies, even the powerhouse Bane at full power.
Saitama is fast, but Superman's faster (faster than light). He is also stronger than him – he can lift and move planets out of their orbits. He has laser vision, can read people's thoughts, and is superior to Saitama in almost every possible way.
While Superman could potentially overpower Thor, blows rendered by the mystical Mjolnir would likely impose serious damage on the Kryptonian hero. With his super-speed, the Man of Steel could probably avoid the Thunder God's lightning, but not necessarily, since Thor is just as fast.
It's been shown many times that a wizard can dodge spells. So Saitama would have no trouble remaining untouchable in their fight as he is even faster than Speed-o'-Sound Sonic. If he can jump off the moon and land back on earth in a couple seconds, he would have no trouble winning.
Though he may have had some help along the way, there's no denying Goku's impressive combat portfolio. This makes it hard to that Saitama can beat Goku.
Will he able to destroy it with One Punch? He would find he can't lift it. At best Saitama has demonstrated planetary levels of strength with ease. However, Mjolnir is not something you can lift via strength.
Odin. Effortlessly. Saitama may have overpowered Boros's Collapsing Star Roaring Cannon with his Serious Punch. Which would have destroyed the surface of Earth (manga) / destroyed the entire Earth (anime).
God claims that he can't be destroyed, but Saitama destroys him and the universe with a single overwhelming punch. Fans are left to wonder where One-Punch Man is going to go now that literally nothing exists anymore.
Goku is probably stronger than Thor at full power, but that's debatable. Both of them have amazing energy powers at similar levels, but the Thorforce is a more powerful source of power than Goku's Saiyan genes. Mjolnir is an amazing weapon and Thor is a master of it, giving Thor more combat options than Goku.
As Dragon Ball Ki operates the same for defense as it does offense, then Krillin's signature technique would let him deal a fatal blow to Saitama, who has yet to show power or durability on that level. And anyways, the Destructo Disk's whole selling point is how it can harm opponents far above Krillin himself.
In the end, unless Clark is capable of defeating Saitama in the early stages of their fight, Saitama will be the clear victor. Not only does his limitless potential help him surpass Clark's power, but he could also last longer in combat.
The advantage of Ultra Ego against Saitama is that not only would it allow Vegeta to take Saitama's signature punch, but will make him stronger as a result. In effect, this gives Vegeta the ability to give Saitama a taste of his own medicine.
