As the 12th Chairman of the Hunter Association, Isaac Netero is one of the strongest people in the world of Hunter x Hunter. After years of training, he became the grand master of the Shingen-ryu school of kung fu. He's agile, flexible, durable, and strong as hell. His Nen ability, 100-Type Guanyin Bodhisattva, lets him summon a gigantic Buddhist statue that fights on his behalf. It can crush targets between its palms or unleash a barrage of punches. As a last resort, he can use Zero Hand, which lets the statue concentrate all of its strength into a beam of energy. 

This was not enough to defeat Meruem, but it was enough to do some damage. But Netero did manage to take down the Chimera Ant King using Poor Man's Rose, a chemical weapon that ended Netero's life, but also fatally poisoned Meruem. On top of being strong, he's courageous.