This level is inspired by the classic falling levels from the original games, you have to outrun the ooze as it comes down the screen. No enemies to worry about, just keep moving downwards.
You'll encounter hazards like barriers which you can break open, you'll get a brief tutorial with what you can do, switches to smash to open barriers, moving platforms, a lot of spikes to try and avoid by gliding down if playing as the Dark Queen, not sure what the other characters use for this stage but it's likely the same gliding ability, parts of the floor that will cause you to jump up automatically so you'll have to jump over those and try to not land on them. There are checkpoints which are a blessing in this stage as well as the odd trampoline like stage piece needed for farther progression.
As you have unlimited lives and continues then just keep trying and eventually you'll get to the end of the stage, there are some moments where the level design is purposely twisty to slow you down so try to go as fast as you can.
It isn't impossible but it is an annoying stage in places.