Welp, it looks like Mario and Cappy have taken a detour, as they have a friendly meet up with Bowser. When you gain control, use the hat platforms (callback to the Cascade Kingdom) to enter the arena, where the dinosaur-turtle himself will appear to throw down.
BOSS - Bowser in the Clouds
You have another three-phase boss here in Bowser, who has a little trick up his sleeve - or hat, as you can see. Bowser will being the battle by throwing his hat at you. This attack can actually be deflected by tossing your own hat at it and if it hits, then Bowser’s will flip over. Touch Bowser’s hat and Mario will put it on, which you will be using against the boss himself. However, Bowser will jump away and when he lands, shockwaves will be sent out, so jump over them to avoid taking damage. Chase after Bowser and spam the Y button to punch him when you get within melee range. Punch him enough and Bowser will go flying back, hitting the wall of the arena, which counts as a hit.
When he rejoins the fight, Bowser will begin with the trickery, by making two clones of his hat before throwing them at you. Of course, these are darker and when you hit them, they will disappear; if you need health, then the hats will sometimes drop hearts. Grab the hat again and Bowser will do the shockwave thing, then start tossing giant rocks at you, which can be broken. Hit him again and it’ll start the third phase. There will be more fake hats spawned and Bowser will do one more shockwave. The biggest difference comes when you go to hit Bowser, as he’ll block the first flurry, then do a sweep with his tail, so get ready to jump and continue your assault to finish the fight.
Of course, Bowser doesn’t take his loss lightly and has a nice little surprise for you. His attacks leave your ship in bad shape, as well as stranded on an unknown world.