To be clear, I'm only talking about the Marineford admirals. Idc about Post-TS bs.
You talk about Akainu being unharmed, but Akainu also never did a single ounce of damage to any of them (or at least it was very minimal). The only damage
Marco received was from Garp (which amounted to a boo boo on his face) and
Kizaru's lasers (which could pierce Whitebeard as easily as Marco) after he attempted to help Whitebeard.
The others received scrapes.
We just see
Marco and Vista attack Akainu. Then Akainu seemingly abandons the fight to
attack Luffy, and he's
stopped mid-tracks by Marco, who fights him until Whitebeard
beats the shit out of him.
After that,
one Whitebeard Commander out of the line-up (maybe two) actually fights Akainu and loses. The others didn't fight him by that point.
It's explicit that, while an impressive display, the Admirals were significantly handicapped and not fighting at full power due to fear of collateral damage on Celestial Dragons.
Besides this, we literally get no detail on the fight, Karasu's entire fighting style is sending out crows, and (IIRC) Morley is virtually featless other than stabbing Aramaki.
Considering that Aramaki didn't need to eat for years and absorbs nutrients from his opponents, probably a **** ton more than even Emperors.