Kaido will win, but it wouldn't be a stomp.
Like narratively it shouldn't be a stomp.
Oda has been holding back Yamato from fighting anyone else:
- He refused to reveal her Zoan form let alone her Hybrid form
- He held her back from having a protracted fight with any significant enemy:
- She oneshot Ulti the first time around.
- When Ulti attacked her the second time, Luffy asked her to protect Momonosuke.
- Franky and Hatchan intervened before she and Sasaki could begin fighting
So Oda has been taking deliberate efforts to hide her true combat ability, only giving us small glimpses (Thunder Bagua, Narikabura Arrow, teasing her durability vs Sasaki, her short clash with Luffy, etc.). Oda is saving her true combat ability for a debut. By all indications, that debut would be Vs. Kaido.
If he was going to have Kaido immediately stomp her, he would have let her reveal her abilities against other characters first. Just look at the Scabbards:
- The Sulong Dukes got their hype against Jack's Zoan form.
- The Scabbards got their hype against Kaido's Dragon form
These are characters less important than Yamato, and Oda ensured that he properly hyped them and depicted them as formidable combatants before they were defeated.
Yamato will be similar. She'll lose to Kaido eventually, but not before she shows out first.