Ezzard Charles (x2), Holman Williams (like 6 times), Archie Moore, Fritzie Zivic. Probablysomeone better though EDIT: didn't read the question properly, he lost quite a few of these
Either Langford, Robinson or Charles I believe. I remember a topic like this in the classic a while ago. I'll try and drag it up and find the answer.
Holyfield perhaps? Qawi, Foreman, and Holmes are in already. Tyson's eligible next year and is a lock. That's 4 to start with and I wouldn't be surprised if Moorer and Bowe got in somehwere down the line considering the fact that lesser fighters have made it. Both were heayyweight champions and Moorer was an undefeated champion at light heavy so that helps his case. Assuming that they make it that'll be 6 total HOFers that Holyfield has defeated.
Sugar Ray Robinson, easily. Jake Lamotta Sammy Angott Fritzie Zivic Henry Armstrong Kid Gavilan Rocky Graziano Randy Turpin Gene Fullmer Carmen Basilio