I remember there was a rule about needing to be less than 50% transparent, which I was fine with but now when I tried to put a bit of transparency it made it black, was transparency in textures disabled entirely?

No, but you can't see the textures being transparent unless you turn shaders off, I'm not sure if they are going to fix that or not D:

I miss transparent textures :CCCC
they could make really cool designs n shit. pls fix gaben/hampa

They are allowed as long as it doesnt make playing more difficult for your opponent.

And as kozmo said, you can only see them with shaders on.

I think the generally accepted rule is that the textures must show a defined body shape, or 50% of the texture is non-transparent