Finally, an editor for Yoshi’s Island with graphics! You can edit a whole lot of stuff, like:
• Objects and sprites • Screen exits • Anything in the level header •
This is only a beta version, released for C3. It’ll only keep getting better and better. It opens the .sfc format; just rename your .smc to that to open it.
Note: This needs .NET Framework 4.0.
File download: