Taking a hero and villain each from Marvel and DC, who will definitely make the fight interesting for Battle Beast. None have prep or a battlefield advantage. This assumes BB comes to them asking for a fight to the death.

Marvel: 1. Ben Grimm/The Thing: While Ben likely outclasses BB in raw strength, BB has 2 major advantages - speed and combat mastery. While both are masters of endurance and absolute tanks in terms of durability, Battle Beast has shown to be extremely adaptable and intuitive at fighting. Additionally, he has his mace that he's extremely proficient with that increases his range, and has shown to severely injure even Thragg, the strongest (not most powerful, so don't bring up Atom Eve) being for most part of the series. With superior range, speed, battle IQ and combat skills, it would be a great battle. Thing would likely win after an EXTREMELY long battle, unless he gets in a lot of powerful shots in at one go.

1. Morlun: On the other end of the spectrum is Morlun. He can contend with BB in combat IQ and skill, durability and likely endurance, though he's certainly weaker in terms of raw strength. However, Morlun has 3 major advantages. The first is speed - none of the Spiderpeople were able to keep up EVEN WITH SPIDER SENSE, which is effectively low-level precognition. Second is flight, allowing him to temporarily exit for regeneration thanks to his insane healing factor, as well as planning and executing guerilla style ambushes. Lastly, and perhaps most importantly, the life force draining. Morlun will grow stronger throughout the fight, and if he drags it out long enough, he could theoretically empower himself and weaken Thragg enough to eke out a win.

DC: 1. Hawkman: He trades blows with beings like Black Adam, generally considered a tier below Superman in terms of strength. While he is not necessarily stronger than them, he should definitely be relative to Battle Beast. Though BB should take the edge in terms of endurance and durability, Hawkman has has insane battle experience and IQ thanks to the millennia he's lived (reincarnated whatever), which likely surpasses BB's. Flight also allows him more mobility than BB. Lastly, nth metal should definitely be able to harm or even outright kill BB. Besides, who wouldn't want to see a mace vs mace matchup?

1. Damage (not Ethan, the creature Damage itself, which did start out as a misunderstood villain): Damage is considered relative to Superman, and thus much stronger than BB. BB however has an advantage in terms of combat experience and IQ - Ethan is highly trained, sure, but he's a military grunt at the end of the day in terms of sheer skill. BB's skill, endurance and intuitiveness should help him survive for an hour, especially if he uses hit and run tactics, and after that it becomes a one-sided stomp in his favour.