Since Two Face may not share the brawn of Bane or the deviant mind of the Joker, he is often overlooked as a credible threat in Batman's rogue's gallery. While it's true that Two Face's expertise focuses more on organizing goons and hatching schemes than fighting heroes, his martial prowess is usually underplayed as a result.
A tangible means of measuring his strength is by comparing him to the many heroes of the Justice League. Through matching his strength to theirs, one might get a fuller understanding of what the former district attorney is capable of — and what's simply too much.
10 Could Beat - Vigilante
Vigilante's place in the Justice League is an odd one given his liberal usage of guns and absence of superpowers. It also puts him on the same level as Harvey. However, he has seldom captured a villain himself, often serving as a support role to more well known heroes.
Additionally, Two Face was trained in sharpshooting by Deathstroke, allowing him a wider scope of weapons than the cowboy hero's revolvers might match. Thus, he could defeat him through a distance advantage.
9 Would Lose - Martian Manhunter
Given his superhuman qualities, the only way Two Face would stand a chance against the alien superhero would be to exploit his aversion of fire. Given Harvey's criminal connections (notably with Joker, who had interacted with enough of the Justice League's enemies to know the Martian's weakness), it's one he might reasonably know.
However, even if Two Face came with a flamethrower, Manhunter has too many options for him to prudently employ it. He could phase through the floor and appear at the other side, assume another form and deceive him until he could get close, or simply blitz him.
8 Could Beat - Booster Gold
Booster is in a peculiar position. Where he might excel against super powered opponents Two Face would get obliterated by (such as building tall monstrosities), none of his powers would prevent any of Two Face's well timed bullets.
He can create energy shields to defend himself, though those shields are only produced as fast as he can react to a gunshot. While it would only take a well placed blow or two to put Harvey down for the count, it's another example of where the criminal's sharpshooting shines through.
7 Would Lose - Doctor Fate
Doctor Fate may be human, but he has displayed feats which Two Face simply cannot contend with. He can move miles in seconds, out maneuvered both Superman and Martian Manhunter simultaneously, and holds a host of other miscellaneous, reality defying powers to make him a nearly impossible opponent.
Two Face's only chance would be to find a way to remove Doctor Fate's helmet, but given his previously mentioned feats, it would be a tall order even for a powerless peak human.
6 Could Beat - Shining Knight
Much like Vigilante, Shining Knight has no superpowers by which to defeat his foes. His greatest asset is a flying Pegasus, which is regrettably just as vulnerable to bullets as he is. The sixth century hero gallops into battle with only his sword to assist him, rendering him easy prey for someone who comes better prepared.
Should the Shining Knight somehow manage to reach Two Face without being too wounded to fight, he may be in for a shocking surprise. Harvey was trained by Batman himself in hand to hand combat, and against an opponent with a large weapon, confiscating it would be trivial.
5 Would Lose - Green Lantern
Green Lantern shares many of the weaknesses that Booster Gold does; there is a human behind the mask, and he can only create shields as quickly as he can react to Harvey's gun.
Where their paths diverge is both the shields themselves and their function. Once Green Lantern has deployed his shield at the speed of light, he may then convert it to any weapon of his choice, all while safely within the confines of his barrier. If Two Face doesn't defeat him before the fight starts, he won't win at all.
4 Could Beat - Black Canary
Canary's cry makes her more useful than some of the Justice League's more underwhelming members, but practically speaking, it isn't enough to secure her victory against Two Face. If he's given adequate warning, he'd take responsible precautions to render her scream manageable. Even if he isn't, her screech is not enough to secure a victory.
It may earn her a few good body shots, but Two Face has defeated Killer Croc with his bare hands, who has in turn defeated Bane (though the converse has also been true). She could give him a challenge, falling short all the same.
3 Would Lose - Green Arrow
While he may not have powers like many of the opponents Two Face is capable of defeating, Green Arrow's extensive training, creativity, and diverse arsenal is enough to defeat Dent. His skill is on par with Batman's, who has knocked guns from Two Face's hands with batarangs in virtually every encounter, and his hand to hand prowess is not far behind.
His arrows include corrosives, electrical, explosives, cryogenic, and smoke bombs to name a few, enabling him with a diverse scope of ways to defeat the aspiring crime lord. While Two Face may be able to score a lucky shot, it's unlikely he'll ever have the chance.
2 Could Beat - Huntress
Huntress may have the skills she needs to defeat commonplace thugs such as catching knives and commendable marksmanship, but her scarce portfolio of achievements and limited arsenal leaves her likely prey, especially considering she's outclassed in the weapons she does have.
Her achievements are nowhere close to Batman's, who Two Face has put on the defensive more than once. She can discharge her bolts quickly, though not at the speed of a gun. Huntress may put up a good fight for the former district attorney, but it's one she'll ultimately lose.
1 Would Lose - Batman
Two Face is a Batman villain, and more often than not, heroes defeat their nefarious counterparts. As adept at a gun as Two Face might be and as fearless as he is in combat, the Dark Knight's expansive knowledge and martial arts provide a challenge he does not have an answer for.
While Two Face may have had Batman cornered in the past, his vindictive personality would interfere, always leaving his fate to chance. These coin flips have given Batman the chance he needs to devise a counterattack, whether or not the flip worked in his favor.