How do you fuse Nata Taishi in this game? Do you have to do a quest for Elizabeth or what? I've been researching it for a few days and have epic failed over and over, wasting so much money on useless personas.
Without Machine Core given as quest reward, you cannot fuse Nata Taishi. If you follow the Fuse specific Persona quest, you should get it. --- After series of bad lucks, there is always good luck follows. - Syuji Terayama.
Fusion in SMT games is based on arcana and level, it's not specific personas. So if Pyro Jack and Zouchouten give you Mokoi, fuse Pyro with a higher level Chariot and it should give you Vetala. The formula in FES/Nocturne/P4 is the average of the 2 personas levels, so I imagine it's the same in P3P.