the fast modernization or rio de janeiro often leads foreigners to forget that the business culture can take much longer to evolve and catch up with ever faster global technology and modern buildings - and that small businesses still are, and probably always will be, based on people more than anything else.

an excellent resource to dig deeper in local carioca customs and business culture is this page as published by  near shore americas.  

on this link published by Serviço Brasileiro de Apoio às Micro e Pequenas Empresas - sebrae, the document Roteiro para Registro de Sociedade SIMPLES is a very useful step-by-step description of how to create a company with two or more partners.