1. Are Teams Allowed?
2. If so how large can teams be?
3. How are the games going to be ranked? (Creativity, Art, Sound, etc.)
4. How many people are expected to be a part of this jam?
I'd say teams are allowed (Im not going to cap the size) but if your project wins.. umm.. i guess you'll have to rock-paper-scissors for who gets the free game copy, because there's only one of those going. I'm not going to put a limit on team size.
There are categories in Overall, Gameplay, Visuals, Audio, and Theme Adherence.
And I have no clue how many people are going to join the jam, to be totally frank. I've never done this before. It probably won't be many though.
I don't have a problem with projects as long as they aren't NSFW or overly graphically violent (which would be quite hard to achieve in Scratch anyway). If you convert your project to HTML and upload it to itch like that, you can get away with a bit more than if you keep it on the actual Scratch site. It's gonna be hard for people to vote on your game if it gets taken down by an overzealous administrator. Personally I think if it's OK for someone 12-15 to play you're probably alright by me.