After you venture through the Kero Sewers, you find the lair of the monstrous Belome.

Battle Belome

Belome has a lick attack that you can block if you press the button when Belome's tongue has gone up past his nose. He has an attack called Sleep Sauce that temporarily inflicts Sleep on the targeted party member, preventing them from doing anything for a few turns. Belome can also use S'crow Funk, which turns the targeted player into a scarecrow for a few turns, unless that party member is equipped with the Trueform Pin, which prevents the effect. A scarecrow can still use Special attacks and use Defense, but can't use items or normal attacks. Belome can also eat a party member, temporarily removing them from the battle. Belome will spit out the party member after a few turns.

After you defeat Belome, there will be a cutscene, then you will have to navigate the Midas River.