Ball
About
During the Rock Bird arc, Jio and Ball were pitted against each other in a battle. It was here that it was revealed that Ball trained himself everyday in order to match up to Jio's battle abilities. During the fight, Ball surprised everyone by showing just how much he had improved with his O-part, even discovering an advance form of it's effect in the middle of the fight. Although he managed to get Jio to take him seriously (Jio stated that he would not need to use his O-part during the fight, but Ball proved otherwise to Jio and forced him (Jio) to fight seriously) and got a few good hits in, Ball still lost out in the end due to Jio activating Satan's power. His loss was not in vain, however, as Jio acknowledged him as a worthy rival after the fight.
He proved his power and skill as a high ranking OPT once again by taking on the powerful cyclops, Tsubame, with his third eye open, and winning. After this he gained the affection of Mei, although he is not aware of this and thinks she's just acting weird when she watches him with awe. In the Zenom base he fought against Franken and won, using Tricky's magnetic effect to take him apart from the inside out.
While not possessing the same level of physical strength of Jio, Ball has proven himself to be quite a capable fighter. Like Jio, after training with Kirin his reflexes, strength, and awareness were raised greatly. Unlike Jio, however, Ball has displayed a natural talent of handling his O-Part and it has been stated by Kirin and others that Ball's ability to control O-parts was much higher than others, including Jio's. In battle, Ball displays amazing cunning and strategy, using his O-parts magnetism effect to fool his opponents, often coming up with surprising plans in the middle of battle. He was even able to to rival Jio during their fight in the Rock Bird arc. Due to his natural talent with handling, Ball is the one who often pilots the groups transportation vehicles (Source: Wikipedia)