Urgent: Do I need to attach I-20 for 485 filing???

Yes.

Please do so.
Even though you supplied all I-20s in I-140 packages, you better do it again for I-485. Otherwise they can issue RFE or intent to denial notice for asking proof of "out of status" issue. This happened to me.
 
Yes, I did.

My suggestion is to attach a copy of all legal documents (I20s, H1Bs ...) covering from the first day you landed in this country without interruption unless otherwise.
 
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