In the Age of Apocalypse, Guido was devoted to Lila Cheney, far more so than he was in main reality. The two of them operated together as part of Gambit's X-Ternals, a group of thieves and minor troublemakers nipping at the heels of Apocalypse's empire. They mostly spent their time stealing food and other amenities for the downtrodden human population living in poverty in the city streets and sewers. Though he was almost obsessively in love with her, Lila had eyes only for Remy LeBeau. Things got worse for Guido when he was captured by Apocalypse's Infinites and had a bomb implanted in his skull -- he was forced to serve as an informant on his gang's activities, and later was even compelled to betray them outright by kidnapping Charles Lehnsherr, the son of their allies Rogue and Magneto. Rogue would later find Guido with her child and take him back... quite forcibly. Though not stated directly, it seemed quite probable that Carosella died from Rogue's revenge assault.
In the Ultimate Universe, Strong Guy was one of the few mutants not to take the cure and, as a result, he was forced to live on the Utopia reservation alongside a handful of others who also declined the cure. He remained a loyal supporter of Kitty Pryde when she went to war with Jean Grey’s faction of mutants. Afterwards he joined up with Storm and Rogue's group of X-Men who were dragged into a battle against Galactus. Despite feeling a little out of his depth, his incredible strength came in handy when dealing with the planet eater.