Avoid collecting the coins at Point 1. It’s much easier to reach the first Star Coin if you leave them in place. Hit the P Switch to transform the coins into Blocks, then use the Blocks to climb up to the Star Coin.
The second Star Coin is near the spiked ball at Point 2. Wait for the spiked ball to roll away from the Star Coin, then hop down and grab it.
The third Star Coin is located in a hidden area. To find it, enter the red pipe at Point 3.
The Star Coin is floating near the green pipe at the top of the room. Jump along the Caterpillar Blocks as they move through the area. Avoid the spiked balls on your way to the Star Coin, then use the green pipe to leave the area.
Morton Koopa uses his wand to conjure spiked balls, and his slam attack is powerful enough to stun you. Dodge the spiked balls and wait for Morton to perform his slam attack. Just before the impact, jump into the air to avoid its effects. After the slam attack, Morton starts to conjure another spiked ball. While he does, stomp on his head.
After you stomp Morton, he tucks into his shell and leaves the room. Dodge Morton on his way out and wait for his return. Repeat the process until you stomp Morton three times and unlock World Five.