A guide to completing World 3-1 in Super Mario Bros 2 for the Nintendo Entertainment System.
Navigate the Waterfall
Go to the right, jump over the gap, and go through the door. From here, you can optionally fall down below to land on an island in the middle, where there is a door. If you go through the door, you find a lot of tufts of grass. The sixth grass from the right is a Potion. You can either drop it in the middle of the grass to get a lot of coins, or you can take the Potion to the right and drop it on top of the vase, then go through the door and go down the vase to instantly warp to World 5-1. If you didn't warp, go to the right after you exit Subspace, and go through the door to return to the first area.
Make your way up the clouds, where you will encounter several Shyguys. At the top, you find a Pidgit on a flying carpet. When Pidgit swoops down, jump on top of it and throw it so you can use the flying carpet. Quickly go straight up the middle of the screen. Eventually you find a vine up above. Jump and grab the vine and climb up.
Explore the Clouds
There is a shortcut to the boss, but depending on the character you chose, it can be difficult to reach. If you don't want to use the shortcut, skip to the next paragraph. Otherwise, the shortcut is to the left of the vine, but if you are using a character who does not jump far, you will need to go to the right and get a Mushroom Block, then try to throw the Mushroom Block onto one of the smaller clouds to the left of the cloud you're standing on. You yourself can't jump onto the smaller clouds, but the Mushroom Block will stay on them if you throw them there. Stack two Mushroom Blocks on the left side of the first small cloud, then go back down onto the big cloud, hold the run button, then do a Power Squat Jump (crouch until flashing, then jump) to jump back onto the mushrooms while still holding run. Make a running jump from the upper left block that you placed, and you should reach the cloud on the left with a door on it. Go through, bomb the wall to the left, jump up the ledges using Power Squat Jumps if needed until you're above the screen, and go to the left to reach the Red Birdo.
If you decided not to use the shortcut, go to the right from the vine, and you can throw a Mushroom Block or the Shyguy at the grey Panser up above.
After that, don't pull the grass on the hill. Instead, go to the right past a Mushroom Block and another Panser, then don't pull the grass on the ledge on the right or next to the ladder, go down the ladder, and the leftmost grass is a Potion. You can either drop it near the grass to get five coins, or you can drop it next to the left wall so you can get a Mushroom by going up the ladder and going to the right.
Then you can go back up the ladder, go to the left, pull the leftmost grass on the small hill, and drop the potion where you found it. Go through the door, then go to the right to get the Mushroom.
After you exit Subspace, you can go to the right, past the ladder, and go through the door to reach the miniboss, Red Birdo.
Red Birdo
Throughout the battle, be careful not to fall into the pit beneath the platform. As before, Red Birdo spits eggs and sometimes fireballs. Catch an egg and wait for a pause in the eggs/fireballs, then throw the egg at Birdo. When the Crystal Ball appears, take it and go through the Mask Gate on the right. Do Bonus Chance if you got coins, and you'll move on to World 3-2.