Castle of the Big Burt Bros.

Castle of the Big Burt Bros. is the first castle in the game Yoshi's Island DS. As such, it is the easiest castle resembling Burt The Bashful's Fort in Super Mario World 2: Yoshi's Island. The castle bosses are two Burt Brothers that have grown by Kamek's magic. The boss battle is also similar to Burt the Bashful's battle.

Layout
The level starts with a straight path leading to the right, which, in a way or another, shares quite a few similarities with the beginning of Burt the Bashful's castle in the previous game. Much like in said level, Yoshi will come across two yellow Egg Blocks upon making his way right, which are supposed to be hit for egg-getting purposes. The eggs received from said blocks would then be aimed at the two question-mark buckets for coins to be eventually released from them and collected by the player. After that, Yoshi will come up to two yellow pinwheels, which will give him the ability to get some coins atop, some of which are red. By hitting the Winged Cloud in the next area, a ! Switch shall come out of it and prove itself useful for getting the first flower in the level, protected by a post. After that, Yoshi will find nothing but a door on the far right. He will then get access to the next room by entering it, which is essentially known for the introduction of the game's spiky Ball 'N' Chain.

The second flower in the level can be found right in the beginning of this room, on a platform floating above a two-way Ball 'N' Chain operated by Shy Guys. Additionally, an invisible Winged Cloud can be found precisely on the top right corner of the Shy Guy operational cabin, which once hit will reveal five Stars. The flower can be reached once Yoshi reaches an area located further on the right, near the level's Middle Ring. After that, the player must go left jumping from platform to platform until they eventually reach the place. Alternatively, by going right, the player should approach a Baby Mario Character Coin and proceed further through the level, finding some Red Blarggs along the way and eventually reaching a line-guide pinwheel. At the end of the pinwheel ride, Yoshi will find four Red Coins, placed in a row, and the level's third flower, which can be obtained solely by aiming an egg at the left wall for it to bounce off and eventually reach the actual item. Another door can be found on the rightmost area, which Yoshi must enter to continue his journey. Yoshi then finds himself inside a third room, where the fourth flower can be seen being guarded by two Burt Brothers in an area accessible via Flatbed Ferry riding. On the right of such area, Yoshi will find three Egg Blocks, which may come in handy if the player wishes to defeat the Burt Brothers without performing an offensive Ground Pound move.

Going down and marching right from that point, a lava pit will be seen, which Yoshi can cross by riding the two ferries seen floating above the danger. Yoshi will eventually reach an area where a Crate can be found on the top right portion, three Winged Clouds can be seen flying in the middle portion of the top, and a couple of doors can be seen on the rightmost portion; a locked one on the bottom right corner, a regular and one that cannot be entered one on the top right corner, the last two only being accessible via diagonal stairway. The crate can be reached by riding the different ferries to get atop, and it contains the key needed to unlock the door on the bottom right corner of the room. The first two Winged Clouds blow into coins, while the last one blows into diagonal stairs, which will prove themselves useful to assist Yoshi reach the regular door on the top right corner. Upon entering said door, Yoshi will be transported to some kind of dark sewer area, which seemingly is home of a couple of Piranha Plants and Lantern Ghosts. The area lights up, however, when Yoshi manages to defeat all the enemies in the area. Additionally, the last flower in the level can be obtained by the same method. Yoshi then returns to the area he previously was and finally unlocks the door on the bottom right corner. On the other side of it, he will find himself in a somewhat short room, where he will be able to save his progress by hitting the nearest Middle Ring and eventually march to the Boss Door, where two Burt Brothers, alongside Kamek, wait for him.

BOSSES: Big Burt Bros.
As Yoshi enters the boss battle room, he comes across two regular Burt Brothers, that soon will turn into gigantic beasts by the magic of Kamek as he comes up with one of his pre-boss dialogues: "If it isn't the killjoy Yoshi! You're always trying to ruin my fun! But not this time! Burt Brothers! Crush this overgrown lizard!"

Pretty much like Burt the Bashful, these bosses are easily defeated by throwing eggs at them, no matter if they are stacked one on another or simply bouncing around on their own. Their basic attack is bouncing around the room, trying to hit Yoshi. No matter which Burt Brother Yoshi damages, his brother also shares the damage taken, so both Burt Brothers are defeated at the same time even if Yoshi throws eggs at only one Burt Brother. Another similarity to the original Burt the Bashful battle is that an egg-spitting flower can be found at the bottom of the room, spitting eggs every time Yoshi loses one, so as a result, the player never runs out of eggs. The brothers are bound to lose their pants, much like their Super Mario World 2: Yoshi's Island counterpart, every time they are hit, and after five hits they are finally defeated, proving to have been an easy task.