On of the most important rules, based on the fact that the paragraph discussing Unoriginal Content was closest to the top of Submission Guidelines, in the submissions was to post content you personally made, otherwise that work will be treated as unoriginal and you'll be banned, so many asked "How can I use work from someone else?"




Secondly, you have to edit the work so a majority is changed; it is not allowed if it's obvious that the submission is the same as the original (that includes minor code edits & recolours!). In addition, variants of that work have to be in the same submission, otherwise it'll be disabled so you can move it to the primary submission.

In addition to having to include proof of permission  when you used work from someone else, you also have to include proof of unoriginality when reporting a stolen submission, most importantly.

Tl;Dr:

1. Only post content you created
   
2. If you want to use someone else's work in yours, you need permission from the OP with proof of it at the top of the post
   
3. You also have to have a majority of the original changed
   
4. (that possibly excludes recolours or minor edits (resource packs) to code (mods) to be considered a "significant amount of the original work edited")
   
   
5. Variants of it belong in the same submission
   
6. When reporting submissions that are stolen, include proof