We are hard limited to a certain number of characters here, so we can only experience the Generation fights so many times...but in these good ol' days, they were actually challenging and fun (not just a chore).
So I came up with a raw idea to implement a way to refight previous generation bosses that seems pretty solid for the most part. Here's a rough description.
The good old crystal ball. Known only for re-watching those snazzy cutscenes you or your party leader probably skipped or didn't skip. Nobody uses these things, let's face it. This is an opportunity to give them a facelift. We could make it to where they can allow you to "rewatch" your Generation Boss fights. How? It's simple for each generation.
G1: Gives a "Albey Dungeon Pass for Memory Replication": You goto Albey, drop the pass, and it just spawns you infront of the boss room with the boss key inhand. Go in, and suddenly, Glas Glabllelelelblebelblblheann. Then, when it eventually dies, the dungeon ends as normal. No rewards really, just some good old fun.
G2: Same thing. Gives a "Barri Dungeon Pass for Memory Replication"...except get this. It's with Tartar-sauce-us. And Esras too.
G3: Again, same thing. Gives a "Baol Dungeon Pass for Memory Replication"...you drop it on the Baol Altar and then suddenly...Cromm Crotch.
G7: There's no boss for this. LUL
G8: Gives you a quest that allows you to enter Renes Cave and fight Crumena again.
G9: Gives you a shadow mission that has just Claimh Solas in the Town Square.
G10/11/12 - Same thing.
I say it would be quite a fun thing to do when you're bored. Perhaps you could even scale the difficulty if you want to challenge yourself for some reason.
Again I just pulled this idea out of my ass and it's no way refined...comment your opinions/changes below.