Comics are not exactly the medium we go to when we want realism and strict adherence to currently known laws of physics. It's an escapist form of fiction, after all - one where people can run faster than the speed of sound without getting their face torn off.
However, comic book writers are also notorious for breaking the already-stretched laws of physics that they have set in their medium, not shying away from over-representing what characters can do. Sometimes this just results in slight miscalculations on how strong a spider should be relative to its size, but sometimes we get things that make as much sense as a boy who's so strong he brought a dead character back to life by punching reality into pieces.
What's more interesting is that while comic book writers are too busy giving various characters the Eric Cartman power, they tend to miss out on some characters who are actually more powerful if they just took the time to understand the powers that they already have, such as:
Jamie Madrox has the ability to absorb kinetic energy (anything from snapping his fingers to stomping his foot will do) and use it to create clones of himself. Not illusory copies, mind you. Actual clones of Jamie the person with independent thoughts and memories. Any of the clones could die without harming the original (referred to as Jamie prime), but when he reabsorbs them, he gains all of their knowledge, skill, and memories. It used to be that he was limited to 50 copies, but he has since broken said hard limit.
Since Jamie is a normal human outside of his self-replicating abilities, most people just write him off as the ultimate cannon fodder. When someone like the Juggernaut appears at the X-mansion, Jamie is the guy who will give him 100 people to punch into space while they're waiting for Colossus to finish getting dressed.
What makes the Multiple Man much more powerful and useful than his name implies is not just his ability to make copies of himself, but also the ability to absorb all the skill and knowledge of the copies. He can create 200 people, order some of them to study science real hard, order some to practice different forms of martial arts, and ask the rest to take various jobs and save money. A year later they all come back and get reabsorbed so Jamie can become Batman. Afterwards he can create copies of himself and he'll have an entire army of Batmen.
Aquaman gets a bad rap because people kept focusing on his more gimmicky powers. Things got worse when the Superfriends cartoon rolled along, as the show basically relegated him to the role of "guy who dresses weird and talks to fish." That's the same powerset possessed by a hobo doing drugs in front of an aquarium.
Later on, they tried to put some credibility into the character by underscoring his ability to control fearsome sea creatures and his role as the figurehead of an entire undersea kingdom.
Getting backup from whales and giant squids is good and all when they're fighting underwater, but once the fight reaches land or outer space, bringing the whales and giant squids along is worse than useless, they're actually unfair to the poor sea creatures who now have to die from anoxia.
As for having an entire army under his command, just think of Darth Vader. Is he feared throughout the galaxy because he has an army under his command?
What many writers forget about Aquaman is that he's far from useless in a straight fisticuff. To understand why, you just need to remember that he survives and functions well in environments where the water pressure is strong enough to crush normal people like a grape. On land, he's probably fast enough to catch your car on foot, and strong enough to tear its doors off with his bare hands.
You might be surprised to find the last son of Krypton on this list. For one thing, he's the poster boy for being overpowered. He went from merely being faster than a speeding bullet and able to leap tall buildings in a single bound to being able to fly to the center of the sun, in a fraction of the time it takes you to commute to work.
The truth is Superman's still being under-represented power-wise, because most people (and writers) only focus on the destructive aspects of his abilities. Sure, he can burn you into cinders with his eyes, and he can punch you so hard your entire family will die, but he's also very, very, intelligent and can move at the speed of light.
First is his intelligence, it's been touched upon by several story arcs and numerous Elseworlds stories, but it's a largely neglected aspect of his Kryptonian physiology that he has a more efficient brain than humans. Some representations of it downplay it as having genius level intellect and an eidetic memory, but the Red Son story explained it better as his brain operating at a much faster pace. Now pair it with the ability to move at the speed of light.
Note the choice of words. Being able to travel at the speed of light is different from moving at the speed of light. The former gets you to a certain destination instantly; the latter allows you to do everything instantly. If you've watched Megamind, that part where Metroman read a book, ate fastfood, did some thinking, and faked his own death in a split second is exactly what Superman can do with his brain and speed.
I believe in saving the best for last, so Magneto gets the last spot. Stan Lee probably didn't realize just how powerful the character was when he gave Magneto complete control over electromagnetism.
To Stan Lee and the writers that came after him, Magneto was just a guy who can throw cars and steel girders around. Even the movie version of Magneto (he can rip all the iron out of your bloodstream, whoop-dee-do) treated him like a shmuck by depicting him as being rendered harmless by a plastic cage.
Much of the confusion comes from people mistaking Magneto's power as "human magnet" instead of what he really is: master of one of the four fundamental forces in the universe.
Not that they haven't tried showing him with abilities beyond being able to stick to a refrigerator. His Ultimate version recently reversed the magnetic pole in order to bring about the end of civilization (although realistically, doing so shouldn't be as catastrophic as the comic would have you believe.)
The glass cage that's meant to hold him captive? It's made up of atoms, which are made up of protons, neutrons, and electrons being held together by magnetic fields. Magneto can manipulate magnetic fields on an atomic scale as shown when he healed Colossus in Uncanny X-Men #212. This mastery of EM on an atomic scale means he can levitate, move and even break anything apart by manipulating the magnetic fields that hold its atoms together, as shown in X-Men Vol. 2 #87 when he dissipated the water molecules of an icicle that was speared through his chest.
Magneto also has control over most of the electromagnetic spectrum (microwaves, terahertz radiation, radio waves, ultraviolet, visible light, infrared, x-rays, and gamma rays.), which allows him to generate or manipulate heat, radio signals, light, and various types of radiation. He also has the ability to sense and control electromagnetic waves, like the ones emitted by the brain's neurons. So technically he can even meddle with your thoughts, though not at the level and accuracy that Professor X can achieve.
Discussing the full extent of Magneto's abilities stemming from his master of EM would require its own article (or two), so let's just cut this short by stating that Magneto is one of the few comic book characters who actually has the Eric Cartman Power.