I want to clear Debu U

It depends on the characters you have, but I recommend including Ramen, Master, Kankan, and Muto. For the upper slots, go for combo characters (HP, Attack, and Speed are recommended). Then, pick any other usable Super Rare characters you have to complete the lineup. Nyanko, Saru Kani Gassen, and Hanasaka Ji are particularly recommended. Good luck!