well in his own title it's just showing why he is like he is, brief rundown of the first 20+ years of his life and how he goes about inventing the suit
In Ultimates he fought the Hulk.... and lost..... he's beaten up a bunch of aliens though
Karate Kid was the master of every form of martial arts to have been developed by the 30th century; his skill in hand-to-hand combat was superhuman, allowing him to simulate super-strength blows. Through training, he could severely damage extremely hard and strong materials--metals, stone, et cetera--with a single blow; he was briefly able to hold his own against Superboy, and once managed to restrain a mind-controlled Kryptonian. He was also skilled with melee weapons, though he rarely needed to use them. He once carved a knife, hilt and all, out of a stone column using only a small rock as a tool, in a few hours. In addition to his physical skills, Val possessed the ability to sense the weakest spot in an object (which may have been why his blows were so effective), like the Marvel character Karnak.
he has Cracked through the hull of the Khund flagship (AD 347), stopped a runaway sport-speedster with one blow (AD 351), knocked out a Jovian Mastodon with one chop (AD 358), cracked through the powerful, six-inch Durlamite gates of the Metroplois Jail (AD 360), damaged tanks with a two-handed chop (AD 360, AD 367), kicked away an air car from the path of a falling boulder (AD 361), split a rock in two and took out an opponent with each piece (AD 361), fought two-dozen assailants at one time (AD 358, AD 361, AD 367) and stamped the ground with both feet, shaking a whole street and knocking a dozen soldiers off their feet (AD 367).
and many more feats.