Batman may have a large family of partners and sidekicks, but Superman is not that different. Over many decades of DC, Superman has been given multiple versions of Superboy, Supergirl, and even Super-Pets, all of which have a wide variety of power levels due to their different backstories and genes.
From the original Man Of Tomorrow to alternate versions of Lois Lane, who is the strongest of the Super-Family, and who is the weakest? To make it simple, this list will only be breaking down characters that have a direct connection to Clark Kent, so characters such as Val-Zod and Ultraman won't count.
Krypto The Super Dog
He's not featured nearly as much anymore, but Krypto was DC's most famous attempt to give Superman an animal sidekick and remains one of the most iconic Super-Pets. He displayed all of the same abilities as any Kryptonian under a yellow sun.
A majority of versions depict Krypto certainly being powerful but not nearly to the degree of actual Kryptonians. There have been stronger versions of Krypto, such as Wolf on the Young Justice animated series.
Steel (John Henry Irons)
After Superman's death, John Henry Irons built an exo-suit and powerful hammer that allowed him to continue Superman's quest for peace and justice. This suit makes him completely bulletproof and he is able to take quite a few hits from powerful villains.
The hammer is also just as advanced and allows him to deal out intense damage. However, take the suit away and John is still a human; a genius and a strong human, but still a human. The Steel suit is not indestructible, even with all the upgrades he's been given over the decades.
Superboy (Conner Kent)
Despite being a clone of Clark Kent, Superboy only has a portion of the power of his brother. This is due to Conner being designed to be half-human with Lex Luthor's DNA. Conner was unable to fly at first, his super strength is not nearly to Superman's level, and even his heat-vision is sometimes depicted as weaker.
That still doesn't stop Conner Kent from being a powerhouse when part of the Teen Titans and Young Justice teams. He can still tear through most alloys on Earth, fight powerful beings, and has the extra benefit of not being affected by Kryptonite.
Steel (Natasha Irons)
One of the lesser-known Super-Family members, Natasha Irons is the niece of John Henry Irons and she too took on the Steel moniker. However, Natasha's Steel armor is far more advanced, able to form in any way she can think of.
Natasha became a member of the Titans and proved to be a powerful member. At one point, she fought many opponents and won on Warworld. However, much like her uncle, without her armor, she is still a human that can be killed by other humans.
Jor-El
He was one of the chief scientists on Krypton before its demise, but he was more than a man in a lab coat. Without the benefit of the yellow sun giving him powers, he was no stronger than the average human, but he has been shown to be able to fight.
In some versions such as Zack Snyder's Man Of Steel, Jor-El possessed a form of martial arts that allowed him to fight General Zod. In the comics, he has displayed tactical analysis and has come to Earth as Mister Oz, displaying the ability to see possible futures, which made him very dangerous.
Superman (Jon Kent)
Over the years, Jon Kent evolved from the new Superboy to the Superman Of Tomorrow. He has displayed that he is able to keep up with his father and even becomes a member of the Justice League in the future, as shown in Future State.
Currently, Jon does not appear to be as powerful as his father, but thanks to Batman, it's revealed that Jon has the potential to exceed Clark. This is why Jon Kent became Superman after his father left Earth, because not only is he strong, but he has one of the strongest wills displayed in the Super-Family.
Superwoman (Lana Lang)
For a period, Lana Lang became a Superwoman, but she did not display the same powers as the average Kryptonian. Lana gained electric-based powers, able to absorb all forms of energy to create electric blasts, travel at extreme speeds like a lightning bolt, and gain invulnerability.
However, Lana's powers weren't stable, and using them would drain her life. Even at all power, she was an impressive metahuman who earned the title of a Superwoman, but in comparison to others, she wasn't nearly as strong. But, that added to her uniqueness as a less-perfect superhero.
Supergirl (Kara Zor-El)
Much like Jon, Kara Zor-El has the potential to be more powerful than Superman. Kara is older than Kal-El but she spent decades in hypersleep, so when she arrived on Earth, Kal was already a fully grown adult. Despite sharing all of the same powers, Superman was able to master his abilities and senses over decades.
Kara arrived as a teenager and has only been under a yellow sun for a brief period by comparison. Her strength is still vast enough to fight Wonder Woman and Superboy. In some cases such as when she was a Red Lantern, her powers elevated past Superman, but as Supergirl, she remains behind her cousin.
Power Girl (Karen Starr)
In terms of power and strength, Power Girl is nearly identical to Kara Zor-El since she is an alternate universe variant of Supergirl. What tips the favor in Power Girl's case is that in her world, Karen was exposed to the radiation of the yellow sun far longer than Kara ever was.
Kara is more agile and more intelligent than Karen, but Power Girl's extra years of experience and yellow radiation absorption give her a slight edge.
Superwoman (Lois Lane)
Over the years, Lois Lane has become a superhero multiple times, but the most famous instance was when Rebirth launched. Sadly, this version of Lois Lane was short-lived but fondly remembered, as she gained the powers of the New 52 Superman after he died.
She was able to absorb Superman's raw power, which allowed her to become Superwoman and do everything that Clark was capable of. Unfortunately, Lois would perish at the hands of Bizarro Superwoman, leaving the moniker to be carried by Lana Lang. If she had lived, fans could have seen this Lois battle the likes of Doomsday or Darkseid.
Supergirl (Lara Lane Kent)
In the Injustice universe, the evil version of Superman almost had a child in the form of Lara Lane Kent. Superman would never get to meet her due to Joker's actions, but she does appear in a dream that is alluded to being a vision of an alternate future.
This Supergirl was raised by Superman and Lois Lane while receiving training from multiple members of the Justice League. She displayed all of Clark's powers but no signs of weakness or downfalls from her human/Kryptonian hybrid nature. This suggests that she might be on the same level as her father.
Superman (Clark Kent)
Superman continues to be one of the most powerful beings in the universe thanks to not only the effects of the yellow sun, but also years of conditioning and experience fighting other powerful beings. Superman has gotten to the point where he could break planets apart with ease.
When battling villains, Superman has to constantly hold back his strength or he would risk murdering everyone with singular punches. This is why he's the often only one who can fight world breakers such as Doomsday. It's also why alternate realities such as Injustice make fans grateful that Superman is the beacon of hope that he is.