Mako was one of the most recurring supporting characters in the Legend Of Korra story. A former member of the Triple Threat Triad and a champion of the Pro-bending arena, his strength is frequently understated, especially when contrasted against the other heroes of the series.
By matching him against a diverse number of opponents, we have a fuller understanding of his strengths and limitations. Moreover, it grants us an appreciation of the many ways he has assisted Korra during her quest to save Republic City from threats, foreign and domestic.
10 Could Beat: Bumi
Bumi was an experienced commander and a capable warrior, the only member of Tenzin's team to escape Unalaq's clutches during their attack on his compound. In addition to his formidable boxing skills, he is also a moderately viable airbender, granting him a versatile arsenal against Mako.
However, his age has frequently been an inhibition during his battles and slows him down noticeably. Since Mako can bend proficiently and is able to apply it into his punches more fluidly than Bumi can return fire, it follows that he would not be able to withstand the young man's power.
9 Would Lose To: Zuko
Zuko is a much more skilled martial combatant than Mako is, demonstrated through his mission to liberate the Boiling Rock, his many encounters against Aang (in which he nearly defeated him), and through his ability to redirect lightning.
The latter would turn the pro-bending champion's most useful weapon against him, as he does not have prior knowledge of the Fire Nation's prince's efficiency in reflecting his power. As admirable as Mako's agility might be, it would be impossible for him to dodge his own lightning, especially moments after he had launched an attack. Therefore, he would seal his own downfall.
8 Could Beat: Sokka
Sokka's skills only increased as the series progressed, becoming a seasoned Kyoshi warrior and mastering the art of the sword. His talent with his boomerang would prove useful, especially on account of its recoil if it misses in its first passing. This would entail that in a direct melee confrontation, he may even get the better of his opponent.
However, his reflexes are not particularly keen (as demonstrated through his defeat by Ty Lee and Mai). Therefore, it follows that he would not be fast enough to dodge Mako's fire and lightning bending.
7 Would Lose To: Korra
Despite the defeats she had suffered, Korra was an efficient Avatar and a pioneer in more ways than one. She was the first to hold the mantle that learned metalbending and had mastered three out of four of the elements with little difficulty.
Even when poisoned, she was capable of matching Zaheer's strength and would have defeated him if her injuries were not exacerbated over time. As fast as Mako's attacks may have been, it would be difficult for him to target her at the speeds she can attain, especially if she launches him into the air with an earthen pillar.
6 Could Beat: Lin Beifong
Under most circumstances, Lin Beifong's metal armor and cables would serve as fantastic utilities to support her already impressive skill. It increases her reach significantly and protects her from many elements (especially water, air, and earth).
However, the metal is an unfortunate conduit for lightning, a fact that Amon's equalists had exploited during their campaign to take the city. As a result, this would make Mako's electrical attacks particularly effective when defeating her.
5 Would Lose To: Yakone
Yakone was a feared crime lord of Republic City. His bending was potent enough to paralyze an entire room of seasoned warriors, including Sokka, Toph, and even Aang himself.
While Mako has demonstrated some resistance against bloodbending (proven through his fight against Amon), Yakone has a greater proficiency in the craft than that his prodigal son. Moreover, the young man's movements would be noticeably strained even if he could manage to resist him, allowing the kingpin ample time to avoid whatever attacks might be directed at him.
4 Could Beat: Tahno
Like Mako, Tahno was a pro-bending champion and one who had found success for several years. He was easily the most skilled of his team, rendering him a worthy challenge despite his posh mannerisms and excessive arrogance.
However, he was completely helpless before Amon (whereas Mako could at least struggle) and resorted to cheating in order to stand a chance against the Fire Ferrets. Both evince that he is an inferior warrior, especially considering that the former triad member was unable to attack him with lightning during their official matches.
3 Would Lose To: Kuvira
Arguably the most skilled metalbender alive (short of Toph), Kuvira was one of the few individuals capable of defeating Korra. She did so without any unfair advantages (such as poisoning or bloodbending), even besting her in the Avatar state in front of a massive army.
Able to detach the plates she wears and use them as makeshift shields, she could defend against Mako's bending expediently. Further, she could also bind his hands with them, negating his ability to resist her iron will and putting him at her mercy. Kuvira's practical military knowledge eclipses his improvised street brawling.
2 Could Beat: Bolin
Mako's battle prowess has reliably been proven to have eclipsed his brother's. During their professional bending matches, Bolin was usually the first to be eliminated, whereas his sibling was the last (sometimes even defeating a team of three by himself).
While the earthbender's newfound lava proficiencies would be a valuable weapon, Bolin is averse to killing (especially his own brother). Though Mako shares similar sentiments, his lightning has been demonstrated not to be lethal against those it targets. Therefore, he would retain his most valuable weapon, whereas his brother would lose his own.
1 Would Lose To: Iroh
Iroh's skills as a firebender overshadowed virtually everyone he encountered. He was so confident in his abilities that he presumed it possible to defeat Fire Lord Ozai himself (only refraining because it would cause further global tensions).
Having taught Zuko how to deflect lightning, he is even more skilled in the craft himself. Further, he commands firebending at greater quantities than Mako does, effectively giving him an edge in every aspect of their fight. Unfortunately for the professional bender, he would not even be able to exploit the former general's age, as Iroh keeps his body in peak condition.