>The main character, Oichi and other special warriors (indicated by gold background) can ‘evolve’ and get a new appearance. To do so, they need a high Link level with their ‘Perfect Link’ Pokemon.
As unrecognizable said they need their perfect link but other things can be nesscary. For some warlords you have to beat their episodes. Some warlords or deputies need another specific warlord in the part like Ina.