I did this in one of my projects... but I didn't back it up before I put in two custom types and moves, and changed the movesets to accomodate them. I even updated the TMs too, but then I removed three unpopular TMs and put in some for the new typings, and then listed fakemon in all the TMs (it was my first project, I didn't back up anything). Luckily I still have the sources I used to update the movesets bookmarked on my browser.
I'm sorry, but I can't post links because I never post on PokeCommunity, but if you search "List of modified moves" on Bulbapedia, there is an article on modified moves by generation, from mechanics to power and naming.
There is a Stack Exchange article called "Which Pokemon have had changes to stats, abilities or their movepool in Pokemon Sun/Moon?" that lists moveset and base stat changes from Gen 6 to 7. Although, I'm sure there were changes from 4-5 and 5-6 that would likely have to be included in your project, but you're on your own for those. I think Essentials might even need 3-4 changes, since a lot of it was built on gen 3.
Would be nice if someone posted a resource of updated vanilla moves, movesets, base stat totals, abilities and TMs to current gen.