The Download Link for the Practice Rom can be found Here.
To install this on a 3DS, you will need to homebrew your console and get Luma Custom Firmware, which can be done by following this guide.
Once you have Luma installed, extract the downloaded zip to the root of your SD Card
Once there, go into the luma folder and then go into the titles folder
Replace TITLE ID HERE with the title ID of your version, which is as following:
EUR Standard 000400000007AF00
USA Standard 000400000007AE00
JPN Standard 000400000007AD00
KOR 00040000000B8900
USA Gold Edition 0004000000137E00
EUR Special Edition 0004000000137F00
JPN Special Edition 0000400000137D00
When you boot up your 3ds, make sure that you hold select and that Enable game patching is on from the Luma menu
Launch the game, and you should be able to use the pipes. If you want to play on vanilla, all you need to do is disable Enable game patching when turning on your console and holding select.
From there, all you need to do is load the level you want to practice, and use any pipes or other useful features the level has.
This is the first of its kind, meaning all the features are new to this hack! This includes:
Pipes to reload or warp to sections you want to practice.
Power up blocks placed in a few places to make practicing more efficient with it.
Red Pipes indicate boss warps.
Custom title screen text to make the practice rom stand out more.
This hack was made entirely by me, Saria_100.
Input and feedback was given by J_duude