If we're talking about unstaged fighting, then some are obvious:

Ford over Cleveland. Ford was an athlete and a Navy man. Cleveland was, frankly, kinda fat. He has a significant edge in weight, but he's shorter and lacks power. No contest.

Jackson over Lincoln. Both of these guys were skinny and sickly as president, but Jackson was a much tougher guy with a military background. Also a known fighter.

Obama over JFK. 'Cause JFK was as sickly as US presidents come, and Obama wasn't. Honestly, it seems pretty likely that Kennedy's team of doctors convince him to forfeit the bout.

Teddy over Wilson. 'Cause he's Teddy. Duh.

LBJ over Nixon. Bigger. More direct and aggressive personality. Has everything going for him.

The others are tougher to call. Clinton/Bush could definitely go either way. Similar size and physical conditioning if we give Clinton for his mid-term fitness, after he became scared to die and got into shape. Same goes for Papa Bush against Washington. Both tough older guys in decent condition for their age and of similar size and apparent strength. Bush has a little weight on Washington, but GW seems wiry. The exact opposite problem occurs in Trump/Reagan - too old, too little conditioning. Winner is whoever doesn't have a heart attack in the 3rd round.

Trump/Reagan shouldn't even be a bout. I think the public would rather see Eisenhower against US Grant (Generals and all...)

Grant's too little and personally wimpy. Let's get William Henry Harrison in there!

next match -
teddy roosevelt vs. woodrow wilson......could be a bloodbath.

TEDDY ROOSEVELT VS. WOODROW WILSON

tr is managed by ric flair.....w.w. is managed by henry kissinger
the bell rings and tr rushes out..wilson comes out cautiously......tr lashes out with a strong forearm to the chest dazing wilson.....tr picks wilson up and slams him to the mat....instead of going for the immediate pin tr puts wilson into a sleeper hold and wilson is dozing in seconds...granny clampett raises both arms of wilson and they fall to his side...52 seconds and the winner easily is teddy roosevelt.....TR advances.

next battle will be George Washington vs. George Bush 1.

THE BATTLE OF GEORGETOWN

this match portends to be hard fought between 2 respected presidents who respect each other...the stalwart founding father who was our greatest president until Lincoln and Bush 1 who was a gritty pragmatic underrated chief executive.
to be continued.
the bell rings and the match begins...Washington stands tall...they do a test of strength ( interlocking right hands until one is forced to the ground ) GW easily bests GB...GW swings bush into the ropes and he gets caught on the way back with a chop against the throat...bush continues to endure punishment until he catches Washington from behind and pulls his legs out from under him and then twists and contorts his legs causing excrutiating pain...Washington using his superior strength and pulls himself to the ropes and forces a break...they trade blows until the 7 minute mark...bush is tiring and Washington suddenly unleashes the cherry tree chopper..he runs against the the opposing ropes and bounces off delivering a very effective drop kick knocking bush off his feet and he is down..Washington applies the pin and it is over at 7.45........George Washington advances.

gritty is not the right word

not gritty in the physical sense but he was independent esp when he bucked his party and raised taxes...in this day and age i see that as commendable honest behavior and i give him a lot of credit for that.

next match is a main event - Lincoln/Jackson

These results are not credible.

I think he's just making all this stuff up.