At Last, Bowser's Castle!

At Last, Bowser's Castle! is level 5-8 in Yoshi's Island DS, and takes place in Bowser's Castle.

Yoshi and all five babies went through this castle to save Baby Luigi and the other captured infants. Yoshi first had to go on a rocket and go into space to get further into the castle. Then there were five paths; which baby Yoshi currently had determined which path he took as each path revolved around it.

After making his way through one of the paths, Yoshi reaches the top of the castle, where Bowser was supposed to be; however he was not present. Baby Bowser wanted the treasure in the castle and thought that the others were going to get the treasure, so he attacked them.

After Yoshi defeating Baby Bowser, the future Bowser got angry with him and they battled. After Yoshi defeated Bowser, Kamek turned him into Giant Bowser. A pink, yellow and Purple Yoshi joined, and they and all the babies (except Baby Bowser) fought Giant Bowser. They each were given a large Yoshi egg. To defeat Bowser, all four eggs were thrown at Bowser at once. The only supply of big eggs the player had were on a balloon. Yoshi had to throw them six times at Bowser to defeat him.

Trivia

 * Oddly, If the player dies in the final boss fight playing as Baby Wario, the player will be unable to play as him if they choose to try again. The reason for this is unknown.