SpoilerThough not particularly strong, he managed to beat Goku in battle due to the heart virus that he had contracted. #19 almost killed Goku by draining him of his energy, but he was interrupted by Vegeta who proceeded to beat him quite effortlessly. Vegeta then transformed into a Super Saiyan and taunted him mercilessly. After #19 had his energy absorbing hands literally yanked off by Vegeta, he tried to flee only to be vaporized by Vegeta's "big bang attack" leaving only his head behind.
Many years later, in Dragon Ball GT, everyone escapes from Hell and Android 19 is among them. He is easily defeated by energy blasts from Son Goten and Trunks, the son of Vegeta.