Firstly, AVA i.e Advertised before Acceptance does not amount to Registration of a Trade Mark and moreover the same is done for the reason of invoking opposition(s), just like the one you are contemplating currently.
Secondly, Proprietor's Code / Agent's Code in the TM 5 form is the space allotted for identifying the person making the opposition and the same is assigned by the Trade Marks Registry.
Thirdly, one commits no crime or civil wrong by filing his Trade Mark for registration and hence no Criminal Complaint or Civil Suit will be substantial solely on this ground. TM5 is the only option you have to impede the registration of the other party. In case the registration is already done,you can initiate a Cancellation Proceeding before the Ld. Registrar of Trade Marks in the concerned Trade Marks Registry.
I hope I am clear to you. Should there be any further question(s) please feel free to ask .