Metal Bat is a S-Class, rank 16 hero for the Heroes Association

As an S-Class hero, Metal Bat is very powerful. Despite his brash nature he seems to be very perceptive, as he was the first one to discover Melzalgald's weakness.

It's believed he's one of the strongest S-Class heroes, as he was able to threat Handsome Mask with little fear, one of the strongest characters in the series, even more than some S Class Heroes.

Metal Bat appears to have a great deal of confidence in himself stating that he did not care whether a threat is a Demon or Dragon level, he would take care of it himself. He also seems to be brash and reckless, as shown when he immediately smashed one of Melzageld's marbles instead of trying to analyze what purpose it serves for the enemy. The way he speaks is like of a pirate accent, pronouncing 'yer' instead of 'your' for example. Despite his brash attitude, he still have a soft side in him, such as toward his sister. Like Saitama, he doesn't care about his rank as well, as well when he challenged Handsomely Masked Sweet Mask for his mockery attitude before it was interrupted by a call from his sister and Sweet Mask's client.

It's your typical highschool thug/delinquent. Try and sound like a stereotypical highschool jock or some kind of hoodlum sounding tone. His speech pattern has slang in it, so maybe a Boston or New Yorker accent could work. 

Think of "The Scout" from Team Fortress 2 for reference.