List of Yoshi's Island DS pre-release and unused content
From the Super Mario Wiki
This is a list of pre-release and unused content for the game Yoshi's Island DS.
When originally announced at E3 2006, Yoshi's Island DS was tentatively titled Yoshi's Island 2. The game's early box art also featured a Nintendo Wi-Fi Connection logo, implying that this game was at one point going to have Wi-Fi features that were scrapped before the final version was released.
In the E3 2006 demo build, players could only defeat enemies while jumping on them with Baby Mario. This was changed by the final version, and the player can defeat enemies regardless of the baby. Baby Peach's cry was also going to sound more adult-like.
An early screenshot showcasing a battle with Big Guy the Stilted seems to suggest that Big Guy was once going to be organic, as he had no patches on him in that picture (although one patch is visible near his right foot, which may merely mean his graphics were incomplete at the time).
One screenshot of an unknown origin shows a Black Yoshi traversing a flowery area with Baby Peach. The particular event illustrated in the picture doesn't seem to be left in the final game. The level "Donuts and Eggs" also wasn't themed in the mid-west, as shown in an early trailer.
Although never used in the game, graphics for Character Coins of Baby Wario and Baby Bowser exist, but they lack animation. Similarly, graphics exist for at least two different title screens, and at least one of them was entirely complete when it was scrapped. It's also worth noting that all were static images, unlike the final game's rotating shot. Two of the scrapped title screens have a Yoshi's Island 2 logo.