For the purposes of moving and taking the control of one bannerman as an attachment with de abbilty of krazhnys wich is his cost. 0 or the printed cost of the card?

thanks in advance

Kraznys mo Nakloz specifies the "printed cost" of the attachment. Even as an attachment, the Banner characters have a printed cost (usually 3) on the cards. So you'd have to pay that cost to use his ability, even though no one will ever pay that cost to make the Banners become attachments.