The rooms in this level are filled with Switch Panels that all must be flipped green in order to proceed. Hit the coin blocks and flip all the Switch Panels then continue along the way to some Stingbies. Defeat them and use the Roulette Block before making your climb up the cliff. Hit all the Switch Panels along the way to open the way via Warp Box. Don’t use it though, instead wall jump up one of the sides to reach a platform above the Warp Box where Green Star #1 is found.
Now use the Warp Box to reach the Checkpoint Flag. The next area is filled with Switch Panels that must be flipped, but be careful with the Biddybuds. Climb up the next cliff and use the Red Ring to collect eight Red Coins for a Power-Up. Head to the left side an into a Mystery Box to a room with a bunch of crates. Destroy the back left ones to reveal Green Star #2 then head to the next area.
Here a Magikoopa guards Green Star #3 so you’ll need to run through the center and defeat it. Run around the edge to collect some Green +Clocks then make your way to the cannon. Launch through the Coin Rings and hit all the Switch Panels in the last room. Climb to the top to find the Stamp then leap to the top of the Goal Pole.