Many heavyweight would beat a 21 years old Mike Tyson something Tyson a student,t of the Boxing ( and fighting in general ) game would be the first to admit .

for starter Mohammed Ali would jab him outbox him all day and either beat him in a very confortable decision or finish him in 7–8 rounds .

Foreman would murder Prime Tyson like he did Joe Frazier he is a nightmare match-up for Tyson who didn ’t want any piece of an old Foreman let alone a young one .

Lewis size jab, movements and IQ would have been too much for any version of Tyson to beat

Rocky Marciano better conditioning and toughness would have allow to whistand the assaults of Tyson and got him in the late round

Sonny Liston forget about it everything Tyson have including the threatening aura pale in comparaison of Liston who eats bullies like Tyson for Lunch .I haven’t seen enough the likes of Joe Louis , Jack Dempsey or Gene Tunney to make my opinion if Tyson would beat them

From what I see The only heavyweights all time great I think Tyson would have a solid chances to beat at their best would be Holmes ( who himself said he would not beat prime Tyson ) ,Vladimir Klitchsko ( I think it’s 70/30 for Tyson ) and Frazier ( 55/45 for Joe Frazier )

All the guy I mention I would bet my monthly wage they would beat a 21 year old Tyson . Tyson prime was scary but the best he was sure not