What if multiplayer was in Mario Maker?

(Repost because I got confused by the lack of a "Maker Discussion" flair. Don't ask.) A month a ago I was asking a youtuber if they could play Mario Maker on their channel. I suggested that this youtuber make levels to completely troll his friends, as his channel and personality is mainly about trolling people. This person is also a famous Minecraft map maker, making over 12 amazing parkour maps in two years. It got me thinking how great they'd be at making levels. But then I remember that he built those Minecraft maps with other people, and it got me thinking: What if there was multiplayer in Mario Maker?

A month later, now that I have a new account that can post on this subreddit, I can actually ask the question...and give my opinions on it too.

First off, lets talk about level creation(with multiplayer).

In the Course Maker, you could "share" the level with other users and they could modify it in anyway. That way people could make levels together. Obviously, only the person who created the course and submit it. You could also give your friends certain permissions like creating blocks and deleting blocks so they don't abandon your trust and ruin the course.

Did you think I'd forget everything else about Mario Maker? Nope. When playing other people's courses, you could be able play it with up to three other players. This would make the Super Expert courses a whole lot easier, because your friends are solving puzzles with you. In five year old made courses where there's just a bunch of stacked Bowsers and enemies, it would get done quicker because there's more people. As for how to do that, you could simply friend other Miiverse users and "invite" them to a party. When you select a course, your whole party is sent into that course.

Here's some other ideas I couldn't categorize:

In autoscroller levels, everybody would obviously be on the same screen as everyone else. But in normal levels, since you can go backwards in all the playstyles, there's no limit as to how far away a player can be. There could also be arrow pointing as to where the other players are in the level, or up/down if they're in a different sub level.

(Yes, I did get the idea from Kirby and The Amazing Mirror)

What do you guys think? Do you have any other ideas for what multiplayer would be like? Comment down below!