Big Mom was one of the pirates who have defeated Kaido, but that doesn't mean she could still defeat him knowing that he already had claimed the title the “strongest creature”. Both pirates are untouchable but Kaido is more durable since he fell from the sky once and stood up unscathed.
Throughout the arc, Oda set the precedent for the generation of the old and brittle to crumble to the new and rising powers. Immediately after, fans saw Law and Kid team up against Big Mom and take her down. This was soon followed by Luffy awakening his Devil Fruit and taking Kaido down as well.
In terms of pure strength, Kaido is stronger than Big Mom.
It is a known fact that Kaido has lost to his fellow Yonko and the Navy a combined 7 times and been captured a total of 18 times. While Kaido might be the strongest in terms of raw strength, there are definitely those who can beat him a fight.
1) Kaido. Kaido did in fact lose to Luffy's Gear 5 at the end of the Wano Country arc. However, keep in mind that he withstood multiple waves of strong enemies before this final encounter. Luffy was also completely worn out after the fight and fell into a coma for about a week.
After being beaten by Kaido in Kuri, Luffy learned to use Ryou and Advanced Conqueror's Haki. With his newly learned abilities, Luffy was finally able to injure Kaido in a battle.
Garp Is Considered To Be One Of The Strongest Marines. Also renowned as 'Garp The Hero' and 'Garp The Fist', Monkey D. Garp is a Vice-Admiral of the Marines. Being their strongest known member in history, there's no denying that Garp is capable of taking on Kaido.
As for Mihawk vs Kaido , as much as i love Mihawk that fight he would lose. Kaido is just too damn strong. If he had help then probably. Mihawk can't win against Kaido who had insane strength that is enough to destroy half of an island.
Luffy defeating Kaidō has been one of the biggest milestones of his career as a pirate. It officially made him one of the Four Emperors and established him as one of the strongest living characters in the world of One Piece.
However, ultimately, Big Mom is defeated by Eustass Kid and Trafalgar D. Water Law who sent her flying down into an underground magma chamber and caught in a massive volcanic eruption, which presumably killed her. Additionally, Kingbaum is destroyed by Big Mom's summoned sun homie Prometheus.
The end of One Piece's "Wano" arc saw Charlotte Linlin, Captain of the Big Mom Pirates, defeated by Eustass Kid and Trafalgar Law. Her fall -- along with Kaido's defeat -- opened a vacuum of power that was quickly filled by Monkey D. Luffy and Buggy the Clown, respectively.
Yes, he would. Kaido already indirectly stated that pre Gear 5 Luffy was > Big Mom. Can Luffy defeat Mihawk easily with gear 5? Did Luffy actually beat Katakuri because he was stronger, or was it because of plot armor?
For now he is nigh-indestructible, several characters can certainly give him a match, and most users of Haki advanced can theoretically destroy his durability and wounded him, but as stated, Oden Kozuki is the only person in the world to have successfully injured Kaido and make him a big scar in their fight, but even ...
Zoro was strong enough to inflict a permanent scar on Kaido, back in One Piece Chapter 1010. However, the Emperor withstood the attack and delivered his own knockout blow, the Raimei Hakke. By this point, the swordsman had already reached his limits. Zoro has the attack power, but he needs more durability.
Until Sanji becomes an ACoC Haki user, he unfortunately, has almost no chance of defeating Kaido. Luffy wasn't even able to meaningfully damage Kaido until unlocking his ACoC Haki, emphasis on meaningfully.
Mihawk outclassed Zoro when the two fought over Baratie, and even now, he is superior to the straw hat swordsman in terms of skill.
Mihawk is said to be close to the same level as Shanks and is even dubbed as the greatest swordsman, so to say Luffy would defeat Mihawk is still debatable in the eyes of many fans.
It's safe to say that Zoro is not yet at the level needed to reach his goal of defeating Mihawk and becoming the World's Greatest Swordsman.
Yamato was capable of holding back Kaido and that's all an Admiral has to do. Kid and Law took down Linlin, two Admirals would decimate her. Once that happens, Three Admirals at the same time vs Kaido would destroy him in a minute. Admirals also has greater teamwork than two yonko.
Maybe he thus wanted to help out in Marineford but Shanks stopped him because he is the "evil" person in here. Maybe Shanks didn't yet wanted a all out fight against the Marines but in a near future? That's why he immediatly stopped it after he made it to Marineford.
Luffy has already lost to Kaido twice, the first time ending up with him in prison and the second with him being thrown off the floating island in defeat.
With the power of the Goro Goro no Mi, he was practically invincible against everyone there, except for Luffy, who could resist his lightning powers due to his Gomu Gomu no Mi powers. Despite being at a clear disadvantage, Enel was able to defeat Luffy once.
1 Almost Nothing Could Penetrate Kaido's Skin
Aside from advanced Haki, the only thing capable of harming Kaido is a world-class swordsman and equally renowned blade. This was seen from his clashes with Zoro and Oden, both whom he admired for their unusually high strength.
It's something fans never would have expected to see after Luffy took the first two losses against the Emperor in the arc previously, and it's taken in an even more surprising direction when Kaido started to reveal that he actually has some respect for Luffy.