Hybrid has been specifically hyped up to be better, especially in this fight. Why would Oda hide a weaker Kaido for later? Anyone with some common sense understands that Oda is trying to hype up Kaido's hybrid form.
If Mihawk has ability to one shot kill Kaido and its a matter of who lands a first hit.
Who would it be? The man literally known as "Hawk Eyes" Or dumb fuck Kaido who couldn't even block Zoro's Oni Giri properly, and barely dodged Zoro still adjusting to Enma?