Help with mini boss stage [Road trip]

So I'm doing hard difficulty phase 9 (dedede) and I'm stuck in this mid-stage where you have to defeat the most enemies to win. I only get periodical bombs and I'm pretty sure that the mini boss is cheating cause he randomly gets bigger and I've used the Swerve star and couldn't find any items on the map.

Any suggestions? My highest stat is strength but I don't think that any stat could improve this situation.