World 2-1
In the beginning of the level, you will notice that there is a cactus in your path. The easiest way to beat this level is to have a fire flower on you and in reserve. Once past the first two cacti, you will get to the first Star Coin. Just jump over the cactus to get it. After passing a few more cacti, they will get platforms to fly up and down on. Don't let this disturb you, because you're only halfway to the end. Jump to get the second Star Coin. After going a little farther, you should see the last Star Coin in plain sight. When you get to the part where you see the pipe, go in and hit the middle block to reveal a switch. Jump over the last cactus to get to the flagpole.
World 2-2
Head right until the second set of rope-like platforms and Koopas. Kill a Lakitu with a fireball or Koopa shell and jump in his cloud. Head up and grab the first Star Coin. For the second Star Coin, destroy the blocks in the way and grab it. Continue to the right and go in the green pipe to be launched up. Press up to go in the yellow pipe. Go in one of the green pipes to reach the third Star Coin. Go back down through the red pipe and finish the level.
World 2-3
Head down the pipe and then to the right. At the yellow arrow pointing down, wall-jump to reach the first Star Coin. Then ground pound the thin disc to continue down. At the place with lots of walls on hinges, head right past the first one, then left and up, go right and down at the end, then left to grab the second Star Coin. Continue to the next screen. Hit the switch to raise the water, and go up. Hit the second switch to go even farther up. Head right for the alternate exit, which leads to World 2-A. For the third Star coin, go back to the water switches, and only hit the first one to continue to the right. At the first branch, head up. Head left, and then up. At the branch, take the right one. Run across to the platform and continue for the third coin. Head back down to the first branch and head right. Go up and hit the red switch. Go across the red blocks to the end of the level and World 2-4.
World 2-A
Head right, and when you see the two different levels of platforms, take the lower one to reach the first Star Coin. Be careful of the big fish. Head to the end and jump from the last spinning platform to grab the second Star Coin. For the normal exit to World 2-Pipe, head down the green pipe. For the third Star Coin and the alternate exit to World 2-Cannon, jump from the last spinning platform. Head as far right as you can, and land upon the Red Koopa as far right as possible to fly up again and reach the yellow pipe. Grab the third Star Coin, head into the red pipe, and finish the level.
World 2-Pipe
Enter this to reach World 2-Castle
World 2-Cannon
Enter this to reach World 5
World 2-4
Head right to the green pipe and the Piranha Plant. When in goes back in the pipe, wall-jump to reach the first Star Coin. For an alternate exit to a Mushroom Shop, you must be Mini Mario. Once in the water, head left into the mini warp pipe. Go right and finish the level. For the second Star Coin, go down and right in the water (be careful not to go too low). Go in the red warp pipe. Go right and through another red warp pipe. Head left and grab the second Star Coin. Continue to the right to the Hammer Bros. Kill them and grab the third Star Coin. Then finish the level to continue to World 2-Tower.
World 2-Tower
Head right, up, and left on the rotating platforms. Cling onto the rope and go across. Go up and right on another rotating platform. Go down and right on the next one to grab the first Star Coin. Go back up and left to the other rotating platform. Go left on it and wall-jump up to a secret door. Wall-jump between the vertical beams until you reach a platform. Jump on top of the moving beams and grab the second Star Coin. Wall-jump between another set of beams to reach a door and go through. Hit the red block to make rotating platforms appear. Jump on the first and then the second. Wall-jump between the red pipe and the wall to hit another red block. Let yourself fall and head left and up on the rotating square, then triangle, then rectangle. Jump to grab the third Star Coin. Go back to the red pipe and head through the doors to reach Bowser Jr. Kill Bowser Jr. by jumping on him three times. Watch out for his jump.
World 2-5
Head right, but watch out for the jumping blocks. When you see a trail of coins going up, jump onto the blocks. When the blocks jump, jump to reach the first Star Coin. Continue past the checkpoint. At the last set of grey boxes before the vertically-moving platform, there are 3 blocks. Hit the middle one to reveal a switch. Jump onto a jumping block and then the switch to make blocks appear. Run left on them to grab the second Star Coin. Head right and kill the Boomerang Bro. Let yourself fall in the sand (be careful not to reach the bottom), head right, and come back up where the gray block is (by jumping). Move around to fall to the bottom (be careful of the hole). Head right and grab the third Star Coin. Then come back up and finish the level.
World 2-6
Head right into the red pipe. Get on the wooden platform and stay on it until you see a vertically-moving platform with no Piranha Plant on it. Get on the platform, and jump to get the first Star Coin. Get on the second large platform. Be careful of Piranha Plants and grab the second Star Coin. When the platforms start leaving the screen, get on the vertically-moving platforms and keep heading right. Jump to grab the third Star Coin. Hit the blue and yellow thing at the bottom multiple times to blow away the Piranha Plant. Go through the green warp pipe and finish the level.
World 2-Castle
Wait until the spiked ball go past you and then comes back to fall in the hole. Then head right. Continue past the next large spiked ball and the holes where you can duck from the smaller ones. Wall-jump and hurry to the right to fall and grab the first Star Coin. Get out and go back down. Go through the door at the end. Head right while avoiding bullet bills, and jump on a bullet bill to reach the second Star Coin. Go up the staircase and be careful of the large spiked ball. Grab the rope and throw yourself onto the platform. Hit the block and grab the Mini Mushroom. Go to the right and through the hole to grab the third Star Coin. From here, you can two things: stay as Mini Mario and defeat the boss to unlock World 4, or grab a mushroom in one of the blocks, beat the boss, and unlock World 3. To beat this boss, wait until he comes out with at least three parts and jump on him. If you are Mini Mario, you must do a ground pound. If you find him hard to beat as Mini Mario, get a Mini Mushroom in your reserve and arrive at the boss as normal, Big, or Fire Mario. Hitting him twice while you are normal Mario and then once a Mini Mario will work. As long as you finish the level as Mini Mario, you will unlock World 4. However, a Mini Mushroom cannot be used after you have killed the boss.