Quackerjack has never been a major character but he has been with The V team since the beginning aiding Eddy and Negaduck whether they're helping their bosses Slade and Anti Cosmo against heroes or facing other villains such as Uka Uka.
After the Great Time Travel Adventure and after TGSTT who knew what he's doing. But he was seen again when Slade had his wedding and invited Bender, Skipper and the rest to attend. During this he and the V Team made a deal with the robot and his friends that Bender would help Eddy and the girls and make sure they came out alive and unharmed and they would do a favor for him. That favor was take back Mobius for Princess Sally Acorn.