It's hard to say for sure, but many would argue that it could be Superman. His powers are almost limitless - super strength, flight, heat vision, etc. In a crossover, he would be a force to be reckoned with against most Marvel characters. However, characters like Thor with his godly powers and the ability to control lightning could also give Superman a run for his money.
Another candidate could be Doctor Strange. His mastery of the mystic arts allows him to do incredible things like manipulate time, space, and dimensions. In a crossover, he could potentially use his magic to counter the physical powers of DC characters. He could even trap someone like the Flash in a time - loop or send Superman to another dimension if he had to.
The Sentry is also a very powerful Marvel character. He has the power of a million exploding suns. In a crossover, if he were to go up against someone like Darkseid from DC, it would be an epic battle. The Sentry's raw power might be enough to take on Darkseid's omega beams and other powers, though Darkseid's cunning and strategic mind would also play a big role in such a confrontation.
Chapter 409, ", Atonement Expedition, Independent Kingdom", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter gives readers a real answer by opening on When Matins was escorting Blaywins and the other eight to Rage Owl... and ending on Picking up eight old soldiers and saving a few thousand grace points....
Chapter 323, ", Reject Protracted Battle, Quick Attack Strategy", is the clearest early answer because the buildup finally cashes out in a real clash. The setup is The offensive against the Kingdom of Stefano was an action guided by..., but the pressure keeps building through The conventional troops adopted blitzkrieg tactics, concentrating....
Chapter 428, ", I am the Dominant Bishop!", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter gives readers a real answer by opening on If possible, Gu Hang would rather not drain every world under his... and ending on Gu Hang placed the Black Box into the factory within the Subspace....
Chapter 318, ", Heijian Star Strategy", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. Early on, But even at this stage, it was only a matter of repelling one attack.... By the end, The main reason he could act now was that the political landscape of....
Chapter 274, ", you have a big appetite.", is the clearest early answer because it turns Imperial Taxes's situation into a concrete plot event. The chapter gives readers a real answer by opening on Was Galaraldo, this War Apostle, visiting the Tianma Star Sector for... and ending on Though he does not lead troops directly, according to the Sun Lord,....
Chapter 384, ", it was Gu Hang who bewitched me into rebelling!", is the clearest early answer because it turns Soldier Tag's situation into a concrete plot event. A useful checkpoint is the way the scene starts with In Korolya, he married and had children locally, mixed in local... and follows through with I will report to the Star Domain Government that it was Gu Hang who....
Chapter 311, ", I am a federation person!", is the clearest early answer because it turns Heijian Star's situation into a concrete plot event. The setup is In the Green Valley Region, a group of investigators had just..., but the pressure keeps building through They too had heard the Governor's speech on the broadcast.. Once the chapter lands on The Alliance indeed did not specifically mention what would happen to..., the chapter closes with She made her way up and met Mr.
Chapter 343, ", Creeping City", is the clearest early answer because it pushes Li Kexi into a new phase or setting. The setup is Under the cover of various types of firepower, the soldiers in the..., but the pressure keeps building through Though they suffered significant losses, they still managed to bring....
Chapter 374, ", Alliance Shipyard", is the clearest early answer because a shaky connection becomes usable in the plot. The chapter turns that into something concrete by moving from Gu Hang now draws technology in the ten-thousand-yuan tier, which... to Inside, it can even include a small-scale recycling system and a....
Chapter 297, ", The Rotten Dragon", is the clearest early answer because it turns Rotting Demon Dragon's situation into a concrete plot event. The chapter turns that into something concrete by moving from He had heard that the Gu Family was already discussing selling their... to Evacuate in an orderly fashion!" This voice seemed to carry a certain....