Hiding attachment/system fields on ticket form

Our workflow means that we have a few different ticket forms.

Not every ticket form requires a attachment, subject or description, so I need a way to hide these 3 fields but only on certain forms. 

I do understand that this is not possible on Zendesk, but am thinking there must be a way to do this with coding.

Could anyone offer some example code where they have managed this? Or any tips? 

Zendesk - this is something massively lacking. I hope the ability to do this will be implemented soon.