Gear 5 is Temporary regardless of who Luffy Fights
If Luffy Defeats Jango with Gear 5 & then He gets exhausted, does that mean Luffy vs Jango was a Draw? Ofc not
No need to Cope, Kizaru was taken out with a Single Attack from Gear 5 & was rendered unable to move or continue Fighting.
Luffy simply ran out of Gear 5, just like He would even if He was fighting no one & only uses it to lift something or fly somewhere
Kizaru was 100% Defeated
Luffy wasn't
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One thing is Clear though:
Gear 5 + CoC > Gear 4 + CoC > Gear 2/3 + CoC > Gear 5 > Gear 4 > Gear 3/2
Without CoC, Luffy cannot Defeat Kizaru or any Admiral regardless of which Gear He uses (Unless 5 wasn't Temporary, but for now it is).
But when using CoC, Luffy gets the upper hand, in other words:
Gear 5 + CoC >> Admirals
Gear 4 + CoC >~ Admirals
Gear 2/3 + CoC ~ Admirals
Admirals >~ Gear 5 (No CoC)
Admirals >> Gear 4 (No CoC)
Admirals >>> Gear 2/3 (No CoC)
That's exactly what Luffy vs Kizaru showcased
Luffy can't face Kizaru with Gear 2/3, but even Gear 4 was still much Weaker, however Gear 5 was finally comparable but due to being Temporary, it would eventually Lose
However when Luffy decided to use CoC, Gear 5 One-Shot Kizaru meaning it's too much for him, so Gear 4 + CoC would be a much harder Win for Luffy, and Kizaru is simply Same Level as Gear 2/3 CoC Luffy (Same Luffy who made Kaidou finally consider him among Strongest)