Doug Fischer is a fucking moron....he left out:

Sugar Ray Robinson
Lightest: 134
Heaviest: 168
Span: 34 pounds

Ezzard Charles
Lightest: 157
Heaviest: 204
Span: 47 pounds

Jersey Joe Walcott
Lightest: 158
Heaviest: 201
Span: 43 pounds

Archie Moore
Lightest: 148
Heaviest: 206
Span: 58 pounds

They all fought better competition as they moved up in weight