Mario Shinwa e (Yoiko Original)
From the Super Mario Wiki
マリオ神話へ【よゐこオリジナル】 (Mario Shinwa e (Yoiko Orijinaru), "To a Mario Myth (Yoiko Original)") is an official course in Course World in Super Mario Maker 2. It is a "standard" level published by NintendoJP and created by Yoiko in episodes 4 and 5 of their web video series Yoiko no Mario Maker de Shokunin Seikatsu. It is set in the Super Mario Bros. 3 style, in the forest theme in the main area and the castle theme for the sub area.
There are five Key Coins which must be collected in this level. One is found at the beginning near a Note Block. Mario can use the three Trampolines at the start to reach the coin. Next are some Brick Blocks forming katakana that read 「ココカラ ラクーーーー!!」 (Koko kara raku----!!, "It's easy from here!!") over a Conveyor Belt. Mario then needs to get into the water and swim through a set of images designed to look like a person, a rocket, a truck, a helicopter, and a car, respectively. The rest of the Key Coins can be found scattered throughout this area. To get the last Key Coin, Mario needs to activate the P Switch on the car to turn the Brick Blocks into coins, which also accesses the Key Door. After entering the Key Door, Mario needs to enter the Pipe.
Mario can then drop down on the Donut Blocks, collecting coins. At the very bottom is a ? Block which contains a Super Leaf, a horizontally moving Thwomp, and a Checkpoint Flag. After that is a room with Seesaws on Tracks. Mario needs to dodge Thwomps, Grinders, and Bumpers to get to a few Twisters and Swinging Claws. Here, he gets a Fire Koopa Clown Car and a Buzzy Shell. There is also a 10-Coin which can be collected. Up next is a set of Bill Blasters and parachuting Goombrats, as well as one Big Flying Goombrat. There are also some Big Chain Chomps which fall on Mario. At the very top are two Skewers. Mario needs to shoot a fireball at some Hard Blocks in the right wall and fly back up to another pipe.
Mario should enter the pipe to get to another Checkpoint Flag, another Fire Koopa Clown Car, and another ? Block containing a Fire Flower. He needs to get through a large ice obstacle to get to a Boom Boom, a Big Bowser Jr., and a Big Bowser. On the far right of the area, Cloud Blocks form katakana that read 「カギハクッパ」 (Kagi wa Kuppa, "The key is Bowser"). Mario needs to defeat the Big Bowser to get a Key, which he must then use to open the Key Door to get to the goal.