So mid 2000s i believe I watched this show about a group of like 5 people(late teens?) that would be hired to hunt down monsters and imprison them and they had a monster on their team that they hunted down but then he turned out to be good so he helped them get the other monsters, for some reason when i think of this show i think of the show Totally Spies! so maybe at the same time? It was on cartoon network or nickelodeon, i believe CN though.