The Taskmaster was one of my favorite "B" tier villains. Oh he looked like the usual costumed yahoo but what set him apart at the beginning was that he had a BUSINESS PLAN! His power was a simple though powerful one. He had what her termed "photographic reflexes." He could watch an olympic gymnist do his routine then do that exact routine perfectly. Doesn't take long for him to make himself a master of weapons and unarmed combat. He dresses up like Death at the opera and arms himself with a replica of captain america's shield, Daredevil's baton, a sword, bow and arrows and oh yes.... guns. Being the villain does have some advantages.
But what to do with this amazing ability. Of course he could kick the hell out of any over the hill security guard but its not like his skill set is made for bank robberies or grand plans to take over the world for that matter. That's where the genius of the concept of the Taskmaster takes over. What he does instead is start up a series of schools mostly for henchmen and minions to teach them to at least be half way useful in a fight. He's paid very well and usually he's not bothered by the cops or supers. Oh, sometimes Spiderman or Daredevil would stumble into one of his schools and there would be a fight but it was no big deal specially since the Taskmaster had absolutely no problem running away and starting somewhere else.
Eventually the Taskmaster is forced/persuaded to help the good guys. He begins, for example, training new recruits for the Avengers. A sea change begins not in the character but how he's perceived. Like other popular antiheroes like Deadpool he is becoming "cool." The Taskmaster mini-series continues the trend to the point where the Taskmaster has been retconned into always being a hero. This is done through the medium of amnesia. It seems there's a cost in using his power and that cost is that it shoves other memories into his unconscious. So often he awakes without any knowledge except a sense of guilt that he is "bad." He is then guided by the mysterious Org which has a deeper purpose than teaching glorified thugs.
It was quite a trick of Marvel to give what was once just a snarling crook a sense of pathos. People who do retcons should look over the Taskmaster mini-series to see how it can be done without ripping what originally made the character cool to shreds.