Not 92 percent though, thats way too big imo, i'm thinking like 60-70 percent is a more realistic but big number.
The percentage is about the damage they did comparatively to each other, not the actual damage Kaido received, and the ratio seems fair to me considering that
- Kaido treated Law's gk as if it was insignificant, hence the 2%
- Killer's sonic attack barely had higher effect than Law's gk, hence the 3%
- Kid only slammed Kaido and thus did questionable damage
- Zoro's tatsumaki did superficial damage and had lower portrayal than Luffy's red roc
So when taking into consideration the fact that
- Red Roc had higher feat and portrayal to all their attacks(let's say 5%)
- G4 attacks are much more powerful(let's say 2times = 10%)
- Luffy landed 3 regular g4 attacks(3times 10% = 30%)
- Luffy's final kong gatling attack dealing the most damage, so much Big Mom was so worried it looked like she almost thought he was about to be defeated, i'd say it dealt about 45% damage comparatively to the rest, or more
And when adding them, it leads you to an at least 90% ratio