World 4 in Yoshi's Island DS takes place in the mountains of Yoshi's Island, becoming snowier and colder in the second half as Yoshi scales greater heights. In World 4-5, Baby Bowser encounters Yoshi and his party, and decides to join them on their adventure. However, this alliance is short-lived, as at the end of the world, Baby Bowser abandons the party as he attempts to go off with Kamek. World 4, like all other worlds in the game, has a total of ten levels; six regular, two hidden, and two bosses. The bosses in this world are Six-Face Sal and Big Guy the Stilted.

Level info[edit]

• 4-1: Rock 'n' Fall – This level takes place on the cliffs of Yoshi's Island. Yoshi needs to jump across rocks while avoiding getting crushed by ones coming from above.
• 4-2: High-Speed Cart Race – This level takes place on a high mountain. Yoshi uses a cart to progress through the level.
• 4-3: In the Clouds – This level takes place in the skies of Yoshi's Island where Yoshi has to bounce on clouds to progress though the level.
• 4-4: Six Face Sal's Fort – This level is inside a fortress filled with lava and Fangs, the boss of this level is Six Face Sal.
• 4-5: Friend or Foe? – This level introduces Baby Bowser who can be used to melt ice and light up dark places.
• 4-6: Slip Slidin' Away – This level is on a icy mountain and has a lot of Bumpties which Yoshi must avoid.
• 4-7: Teeth-Chattering Chill Zone – This level involves using the slippery ice as an advantage and as something to beware of, the latter parts of the level introduces Ski Yoshi.
• 4-8: Castle of Big Guy the Stilted – This level takes place in a Castle and involves using Baby Bowser as a shortcut to trigger things that normally require eggs, Big Guy the Stilted is the boss of the castle.
• Secret 4: Hurry and Throw! – This level is inside a castle where the screen autoscrolls in a circle; Yoshi has to run around and collect the three Number Balls to open the door to the next section, where Yoshi has to jump off of the heads of Koopa Paratroopas in the sky.
• Extra 4: Let There Be Light! – A level which begins in a dark fortress with Spikes and Bullet Bills, leading to a space section with Flatbed Ferries, Spinners, and more spikes.

World 5 is the final world in Yoshi's Island DS, before Bowser's Castle. It takes place on a wild gloomy island high above Yoshi's Island. As with all worlds in the game, it contains eight normal levels and two secret levels, one unlocked for beating the game and another for getting 800 points in the world:

The boss at the end of world 5-4 is Moltz the Very Goonie. In the final level, world 5-8, Baby Wario and Baby Bowser rejoin the group as they head into Bowser's Castle. However, at the end, Baby Bowser betrays Yoshi and fights the player, but is defeated. After that, Bowser, in his normal form, shows up and attacks as well. After he is defeated, Kamek uses his magic to enlarge him, much like he did to Baby Bowser in Super Mario World 2: Yoshi's Island. In this final battle, the enormous Bowser is in the distance and the player controls four Yoshis at once, carrying Baby Mario, Baby Peach, Baby Donkey Kong, and Baby Wario and must throw giant eggs at Bowser to defeat him. This is also much as the final boss of the original Yoshi's Island.

Levels[edit]

• 5-1: Rompin', Stompin' Chomps This level takes place on a valley infested with Chomps. The first part of the level is auto-scrolling.
• 5-2: Goonie Heights This level takes place on the cliff with plenty of Goonies. Yoshi must ride the Goonies to progress through the level easier.
• 5-3: Spear Guys' Village Found! This level is in the Spear Guy's Village. It has a lot of Spear Guys and is jungle themed.
• 5-4: The Fort of Moltz the Very Goonie This level takes place in a fortress in the sky. Moltz the Very Goonie is the boss.
• 5-5: The Cave That Never Ends This level takes place in a cave filled with lava, the whole level auto-scrolls and is pretty long.
• 5-6: Find the Number Ball! This level is inside a volcanic lava cavern. Yoshi must find the number balls to exit.
• 5-7: Superhard Acrobatics This level takes place high up in the sky. Yoshi must use his platforming skills and Flutter Jump ability to progress.
• 5-8: At Last, Bowser's Castle! This level takes place in Bowser's Castle in the sky. The boss is Bowser.
• Secret: Yoshi's Island Easter Eggs This level has Yoshi endure a set of very hard trials in castle areas.
• Extra: Quit it Already, Tap-Tap! The final level in the game, the level begins with two Super Big Tap-Tap chases, followed by a Mole Tank section with many Tap-Taps, and ends in a Mine Cart chase with another Super Big Tap-Tap.