Minihud
Every feature is allowed.
Litematica
Most Litematica features are allowed, however EasyPlace is NOT allowed, which is an addition to Litematica that allows you to place blocks in ways that are impossible without it; For example, you can place a block in mid-air with no supporting block.
Item Scroller
Every Feature is allowed. (But please don't go too nuts with the mass Crafting, the game will kick you for sending too many packets)
Tweakeroo
Free cam mode is allowed when used to look inside redstone machines (and for similar uses). It is not allowed when used to gain an unfair advantage, such as (but not limited to) its use to aid in mining or while searching for caves.
Using it for videos on the server is allowed.
Note: If you're not sure if something is allowed, you MUST ask staff, or you may be banned!