World 5 (Puzzle & Dragons: Super Mario Bros. Edition)
From the Super Mario Wiki
World 5 is the fifth world in Puzzle & Dragons: Super Mario Bros. Edition. This world takes place in a forest, resembling that of World 5 from New Super Mario Bros. Wii, with a remixed version of the world theme from that game. Like other worlds in the game, Orbs are scattered about the map. This world consists of twelve levels and a Toad House. Iggy Koopa is the boss of this world and is fought in his castle and airship. Clearing World 5- unlocks Green Yoshi as a Helper, and clearing World 5- unlocks Penguin Mario and Penguin Luigi as Leaders.
A more difficult version of World 5 exists as a Special World: ★World 5.
Upon reaching the dead end in this course, the player may notice a Gold Block to the right. In order to reach the secret exit, the player must take the path of the block - which requires clearing more Dark Orbs than Wood Orbs. This course does not contain any Dark Orbs, however, so the player needs to bring an ally that can create them. Upon taking the path, the player immediately faces the boss. Upon defeating them, the player unlocks World 5-4.