As long as there's no actual *bleep* scene it should be fine. Also you may want to put a warning on it before you post it.

So just for an example, before you get the scene you say "Warning: *bleep* scene?"

Well theres something you can be assure of, none of my fanfictions have *bleep* scenes(thank God).

I have a quick question about the fanfiction. Er, is anything mentioning *bleep* allowed? Or is that against the rules? Because I have a story I wanted to post, but it might not be allowed since it 'fades to black' as the saying goes...

Sometimes such things like this must happen in a story so that something makes sence (usually in prologes to storys where you are telling how a child came about.. ect.)

No descritions here of course.. a mention should be ok though..

Edit: My bad.. realized this was all ready answered by Stormy..

What about gore and violence?

In as controlled a manner as you can. I don't mind it so long as it's not excessive, like I said before if you want stuff that in depth just head over to fanfiction.net, an entire section for Spyro is over there as well.