Every 27 years he wakes up and feeds.  Feeds on the fear of children in Derry, Maine.  Pennywise brings his passion for fear and aggression from the cosmos to the suburbs of Derry.  When he is active, he hunts and just by simply existing for a period of time, he turns up the aggression, hostility, and anger in Derry.  He is a force for everyone in the town.  But Pennywise is much more than a malevolent clown, he is a cosmic force that just happened to land on Earth.  There are other Earths that have individuals that could counter his power.  Earths that have superpowered individuals.  Pennywise could easily give empowered, enhanced or highly skilled characters a great fight.  If Pennywise just so happened to land on an Earth with these people, which superhero would be the best rival for him?

Instinct will say a perfect match for Pennywise would be Batman.  The Dark Knight definitely has history with crazed killers that have a love for the clown aesthetic and others that love to use fear as a weapon.  Having both of those villains combined into one, would be a problem for Batman.  And with the 27-year gap, Pennywise could be a personal threat to Batman.  Pennywise could have tormented a young Bruce Wayne, especially after his parents were killed.  Determined to never be afraid again, a young Bruce Wayne could use his early run in with Pennywise as a drive to overcome his fears as he grew into Batman.  Then 27 years later, Batman and Pennywise clash again but this time, Pennywise fights Batman in his prime.  Plus, Pennywise could easily feed off the hostility that plagues Gotham.  Gotham is already a hostile city but having Pennywise elevate that, would make Gotham a breathing war zone.  A situation that would have Batman call as many hands on deck as he can, be it the Bat Family or the Justice League.  But is the power level unbalance?  Pennywise is a cosmic force while Batman is a street level vigilante.  Batman does punch above his weight pretty consistently and ordinary people were able to defeat Pennywise.  So having Pennywise as a Batman villain makes sense but there are other heroes.

Pennywise also has some crazy powers that could be viewed as supernatural.  He could manipulate environments, shapeshift, alter his size, cast illusions, and doing all of that without even having a true physical form.  The deadlights are an instant fear inducing phenomenon that comes the closest to representing his truest form.  With an entity with abilities like this, someone would have to fight him with fire to match his own.  Characters like Constatine and Dr. Strange/Dr. Fate do come in mind.  These characters are masters of the supernatural arts.  Constatine is an underrated powerhouse that has history with demonic and hellish enemies.  Something that Pennywise could pass for.  Dr. Strange protects Earth from all sorts of supernatural enemies.  Enemies that have raw, nearly limitless power.  He fights these threats that come from other realms, dimensions and realities.  Since Pennywise comes from a place that is beyond space so much in fact it is a different pocket of reality, Pennywise could be treated as a familiar threat to Dr. Strange.  Pennywise is a creature that capitalizes and runs on types of chaos.  Whether it’s chaos itself, aggression, pandemonium, hatred or fear, it’s up for grabs for Pennywise.  A powerful agent of Order, someone fated to fight chaos no matter its form, is Dr. Fate.  Dr. Fate goes up against anyone or anything that causes chaos.  Pennywise is such a character and thrives on it and creates it himself.  This is a perfect formula to make the Helmet of Fate and Pennywise eternal enemies.  Supernatural based characters are logical choices to fight against Pennywise but even though he could come across as that, his origins come from space.  His rival should come from there.

Pennywise is a cosmic threat that preys on fear.  Uses it in fact.  There is a hero, actually a core of heroes that originate from the cosmos that serve as an intergalactic space force that are sworn enemies of fear.  That is Green Lantern and the Green Lantern Corps.  The number one enemy of the Green Lantern Corps is fear.  Pennywise uses fear as a means.  Green Lanterns patrol all areas of the universe, Pennywise comes from beyond but their paths could easily cross.  Pennywise could jump planet to planet invoking and feeding off fear while selected Green Lanterns are tasked to track him down and finish him.  But since Pennywise is a force rather than a physical body, many Green Lanterns fall to him.  Then, when Pennywise gets to Earth he has an inevitable clash with the Lanterns that call Earth home.  Pennywise has all the makings to be a serious threat to the Green Lantern Corps. Since Pennywise and the Green Lantern Corps/Guardians of the Universe are old, these two forces of cosmic nature are destined to be eternal enemies.  Several Green Lanterns could be thrown at him or just fated to go up against him, and Pennywise could easily get in their heads, discover who and what they fear and could potentially be their greatest and strongest enemy.  Their power levels could match each other.  And since Pennywise could sense what others fear, create illusions so strong they are in fact real, or shapeshift into those things, that opens the door for any Green Lantern to potentially lose their will, leaving them vulnerable for a fatal blow.  These are two opposing sides that originate from the stars that gain power from two opposing factors. A Pennywise and Green Lanterns rivalry is a perfect match.

Pennywise is antagonistic, villainous, and evil through and through.  It takes a pure, brave soul – or souls – to defeat him.  The world of comic books has a collection of these types of characters.  Most of them have experience with some sides of Pennywise’s character that would make a clash a bit more balanced.  Batman’s and Green Lanterns’ battle with fear gives them a good shot.  And anyone in the supernatural world would have the power to match the power of Pennywise.  Pennywise lives to terrorize and that would put him at odds with some great heroes in the comic book world.