Riddick Bowe wouldn't put up a hard fight vs either brother. He never fought a power puncher his entire career.

Mike Tyson even in 1986 is debateable especially when discussing a Vitali vs Tyson matchup...maybe Mike could get to Wlad early on and follow up, but still it's a big ask.

Young Cassius Clay got damn near KO'd by Henry Cooper. He moved like lightning vs guys like Liston & Cleveland Williams, but the Klitschkos are a touch more athletic than those guys, but erroneous, I will concede the point vs Ali & vs Holmes (though I fully think Vitali & Wlad beat Holmes).

I think the most difficult fighter for either brother to beat is Evander Holyfield just because he's tough for everybody to beat. Evander was awkward to fight especially for an orthodox fighter with such conventional attribute, but he had workrate, solid defense, a head hard as iron, and the heart of a champion.

A younger Shannon Briggs would have been dangerous on HIS day, but then you're just judging potential. I think Shannon Briggs would hammer the shit out of Riddick Bowe.....Bowe is one of the more overrated fighters of all time, given his era Bowe fought NOBODY! No Tyson, no Lewis, no Mercer, no Ruddock, no Rahman, no Tua, NOBODY.

Corrie Sanders on his day is tough for anyone to beat, a big awkward southpaw with loads of power.

George Foreman of course deserves a mention at least because he was strong as an ox and had tremendous power.