As you free the Sprixie Princess you’ll gain access to another clear pipe, but not yet World 4 as a carnival-like structure flies onto the small island you are now located on. Enter the level and grab the Super Bell from the ? Block before going up the steps then into the gondola.
This large snake has a few fellows snakes it likes to call into battle to try and defeat you. Hisstocrat starts by summoning boulders to drop from above, their landing zones indicated by shadows. Avoid them and wait for the smaller snakes to emerge with plates on their heads. Some of these smaller snakes will not have a plate on their head, this is indicated by the eyeball poking out amidst the rustling sand. Ride the snakes high into the air then pounce on Hisstocrat to damage him. You’ll have to do this three times to defeat him and it’s hard without the Cat Power-Up, fortunately some snakes bring Super Bells with them which makes this is a relatively simple boss battle.