Of course it's Zoro deserves to be on the roof. If anybody sure on the roof it should be him.
Oda has been hinting it Zoro defeating Kaido since he killed the dragon in Punk Hazard. The Scabbards stated Kaido won't be defeated until they literally take his head. Kaido is waiting for a strong samurai (swordsman). Zoro is not just a swordsman he has the samurai theme.
Zoro has been the most effective fighter against the Yonkos. He can counter both of their fire attacks and damage them both. He hasn't even mastered enma.
Zoro's dragon twister is a way more efficient attack than Luffy's kong gatling. Luffy's attack used a lot of power and that didn't cause equal damage. He hit Kaido a lot but the damage from each attack was very little. Zoro's caused more damage with one attack. His attack caused internal and external damage to Kaido.
Oda has been hinting it Zoro defeating Kaido since he killed the dragon in Punk Hazard. The Scabbards stated Kaido won't be defeated until they literally take his head. Kaido is waiting for a strong samurai (swordsman). Zoro is not just a swordsman he has the samurai theme.
Zoro has been the most effective fighter against the Yonkos. He can counter both of their fire attacks and damage them both. He hasn't even mastered enma.
Zoro's dragon twister is a way more efficient attack than Luffy's kong gatling. Luffy's attack used a lot of power and that didn't cause equal damage. He hit Kaido a lot but the damage from each attack was very little. Zoro's caused more damage with one attack. His attack caused internal and external damage to Kaido.