I personally would recommend YoshiOP, lots of guides exist for him. As for the fight itself spamming debilitate with Akechi, using MaTarukuja + Charge + God's Hand on Skull with Makoto heals and defense buff.
As for the way to actually fuse a persona like that, the only way I know how is to find the skills you are looking for, then just fusing personas until you funnel all the skills you want into one persona.
Imo you don't need the most optimal set up though, as long as Joker doesn't have any weaknesses to avoid the AoA then your fine. Just remember to heal all the time and bring SP items.
