On panel Marco spent his whole time countering/blocking/kicking their ass. You can’t do anything against that
whe he uses his speed, he is vulnerable. If katakuri knows the hax ability like zoro now knows, then he will use futur sight to track on the fire on his back and would know 5 sec before when it will be on or off.... FS counters well king's ability ngl
He's about as vulnerable as Queen is regularly. Idk why act like King becomes glass cannon when he uses speed. He still has his general Ancient Zoan durability and CoA.
Speed form King tanked several Haoshoku coating attacks from Zoro:
The first of those should be stronger than the attack that scarred Kaido (a Santoryu technique with Haoshoku coating).
Queen is not tanking these attacks.