The Holyfield that still had hair beats everyone except Vitali and Fury. Both know how to fight tall (consistently) and their sizes and awkwardness would give him problems. Wlad and Joshua could crumble under pressure, Wilder ain't good and there's very few people Holyfield's height/size that he didn't eventually turn up and show out against.
On his best day, he probably beats them all. Fury is the most difficult one. Could be a series of fights but I see Holyfield coming out on top
The way I look at these hypothetical match ups, scheduled for 12 rounds, Holyfield brought forward and reconstituted (along with his team) into prime condition for each fight, with time to observe and train, IMO, Evander beats them all.
AJ- Holy TKO 8. Might get dropped. Wlad- Wlad SD, it would be a great fight. Vitali- Holy SD Fury- Holy UD, and Fury would be a mess at the end. Wilder- Holy TKO in 8.
King Kong KO's Holy in 3 Godzilla fries Holy in 2 Rodan gets hit hard early, flies away, giving Holy a DQ.
King Kong was too big and lumbering, like a 65 year old Foreman but way bigger and slower. Holy overwhelms that romantic gorilla and Kong's corner throws in the banana in 7.
Given his actual career, he certainly wouldn't go unbeaten against the current top lot. Not to mention he probably couldn't get away with the same level of PED abuse now.
I would say that he is good enough to be favorite over all of them, but not good enough to beat all of them. I think you know what I mean.