Short answers must be short.But what about the written forms?we mustn't use short forms in writing
*****I mean short answers must be in the contracted forms.
For example:
Yes,I'm.
No I'm not.
Is it wrong to use the short forms in our writings?(short answers must be in the contracted forms)

Question

Answer

Contracted forms are used in informal writing such as email between friends.  Otherwise, the standard forms are used.

Answer

Yes, I'm. - not a usual sentence. --> Yes, I am. (Also space after "." and ",")
No I'm not.
.
I'm is a normal use experession, if informal. If your writing something informal, then I would not be afraid to use such normal contractions.
If you are wrtiting something formal, then yes, I'd also skip these, for the full versions. I'm not sure that everyone form every culture will agree, but that's the answer for me, where I am.