That is an interesting proposal. So best to see what will happen.
considering how difficult justine and caroline are, i have a feeling that they won't give you a chance to fight him because you'd lose. he is the master of the velvet room, you can't stop him.
also, p5r isn't necessarily a remake or whatever.
We don't know what P5R is going to fucking be.
yes you're going to fight Igor, on the racetrack, where he drives his velvet limo, in Persona 5 R(acing All Afternoon)
Persona 2 let you fight Igor's boss, though he barely uses any of his true power in the fight. Based on how that fight works though...Igor would probably be equally as bad if not worse because he wouldn't have to hold back as much.