To be the ultimate navi first you must style change into a grass style and set your regular chip as grass stage. Second in your Custom Navi program you must use the battle chip undershirt. While fighting when you are hurt you will gain hp from the grass stage and when you are almost about to die undershirt makes sure that you survive with 1 hp then the grass stage heals you. Then when you are about to die again it happens over and over and over again giving you the ultimate navi.