You need 155 gems to unlock this level. I have 186.
Toadette finds herself on a metal scaffold. Approach the ladder and the structure will start sinking. There are many Piranha Sprouts on the scaffold, as well as coins. Collect as many as you can. The first gem is on a ledge with rails. Pick the turnips and Piranha Sprouts to grab the stacks of coins without having to run for them. Pass the next ladder and go around it for a pile of coins. There's another pile of coins on a ledge similar to the one where you found the first gem. Drop down past the spikes to find more coins. Go past the next set of spikes and drop down the ladder for a large amount of coins. Go through the gap in the pillars in front of the ladder to find a ramp towards the top of the structure. Drop down and you'll find the second gem. Climb up the ladder next to the spikes for two plants with lots of coins. Just up ahead on a ledge, guarded by some Piranha Sprouts, is a plant with the third gem. Climb the tall ladder. At the top, are two plants with many coins and the Star.
After Toadette gets the Star, Wingo carries her off.
Special Challenge: Collect 200 coins.