The Mushroom Kingdom has been invaded, and the throne room is now home to the gang's leader, Mack.
After you defeat Croco, you will find Mack in the throne room in Mushroom Kingdom.
Mallow should always attack with Thunderbolt. This will defeat the Shysters in one or two turns, and it has a chance of stunning Mack. Mack can make the Shysters reappear sometimes, so be sure to use Thunderbolt again whenever they reappear.
Have Mallow use HP Rain if needed, or you can use Mushrooms to heal up.
Mario should focus all attacks on Mack, and he should attack with Jump, or Super Jump if he has it.
To defend against Mack Jump, press the attack button the moment that Mack lands on your head and you can see his shadow on the floor.
Mack also attacks sometimes with Flame Wall, which hits the whole party, and Flame, which hits one character. You can't defend against these fire attacks.
After the Battle
After the battle, you get a light blue Star Piece.
In the throne room, talk to the chancellor, and there will be a cutscene.
Afterward, be sure to go to the item shop and talk to the shop owner, and now that Mallow got his Frog Coin back, the shopkeeper gives him a Cricket Pie for his grandfather.
You might want to buy some Able Juice from the item shop.
Now go southeast from Mushroom Kingdom and choose Kero Sewers on the map.