fakezaga - Wasn't he known for being hard to hit?
He'd be the Machida of his day. Or maybe the Fitch. People complained his style was boring - but it sure was effective.
And of course he would be athletic and explosive.
He'd be a middle weight Dominic Cruz with better hands, footwork, and a mean clinch game 
GladiatorGannon -FrozenBagOfMicrowaves - He probably would have went 2-9ish in low tier organizations against cans before retiring in shame.
Incredibly gifted athlete that would have been a complete monster with modern training.
Jim Jeffries would have been a monster in his prime. Sam Langford and Jack Dempsey as well.
He was a brilliant boxer, way ahead of his time. He was the first to use headmovement and not just stand and bang.
TTT
Johnson name should come up whenever born athletes are mentioned. He would have a Bones Jones type dominance.
Johnson was more the social game-changer. He was not afraid to be a black man during our ancient times.
Bobby Lupo - He'd become the LHW champion, then refuse to defend against: Bones, Rampage, Rashad, Davis and King Mo. Instead he'd defend against Matt Brown, War Machine, Junie Browning and get Royce Gracie out of retirement for a superfight.
Rampage style IMO
Phisher -kanodogg2 - That dude lived the life man, even in the early 1900s he was a black dude that was railing out white chicks.Not really. He actually got prosecuted and thrown in jail by the federal government for having white girlfriends. Johnson was the first person prosecuted under the Mann Act. Plus, most of his women were rank whores (as in actual prostitutes).