Leonard was and still is considered a defensive master. Are you implying only today's coaches can teach a tight defense? Please tell me I'm misunderstanding you here because I haven't seen too many defensive masters lately.
Pep, Benny Leonard, JJ Walcott, Wilde, Locche have already been mentioned. I take issue with the mentions of Ali, Pastrano, and Dupas. To me, they were more runners than slippers. Not meaning they were unskilled, but they didn't hang in there very much to counter the miss after slipping the punches. They'd dance away and create their own opportunities later. I'd put Del Flanagan and Sugar Ray Leonard in that same category. New offerings -- Mike Gibbons, Billy Petrolle, Jimmy McLarnin, Tony Canzoneri, Jock Malone, Billy Graham, maybe Barney Ross, Henry Armstrong, Joey Giardello, Carmen Basilio, Harry (Kid) Matthews, Greg Haugen. These are fighters who would invite leads in order to counter. I admit that these are among my favorite fighters. Henry Hank and Joe Frazier, too. Lloyd Marshall and my take on Tiger Jack Fox (even though I have never seen a film) are of fighters who held their hands low and moved slow to invite a lead, which they would try to slip in order to land the heavy artillery. I'd put Langford in this category, too. These guys are also favorites of mine. Seems to me some of the Australian fighters like Dave Sands fought in this style, too. Robbie Peden when he first came over here fought aggressively and slipped punches, though I think he later was told he would have more success by changing his style.
My one quibble with Pernell Whitaker was that he used too much unnecessary movement at times so that he wasn't in position to counter and make his opponents pay for their misses, even when they were otherwise close enough to be in his punching range. But it sure was fun to watch, and I guess you can get away with it when you have that type of talent and ring IQ.