Note: You must first have all three other characters besides Yoshi. Change into Yoshi and jump into the painting about halfway. You will be on the floating platform when you enter and be able to see a ramp due northwest of your location. Get onto the ramp and go to the thing that tosses you up to the next level. Once you get past the wind-up purple Bomb-Omb thing, get to the pink Bomb-Omb that sets up the cannon. Fly over General Goomba (the Goomba with Wario's hat) and turn around so that he knows you are there, but will run into the corner. If done long enough, General Goomba will commit suicide by blowing himself up. Also, if General Goomba notices you when you are right next to the pink Bomb-Omb, he will try to get to you and eventually commit suicide without you really being able to see.