Was adding the Fairy Type particularly useful? Not that I mind, but all of the type's damaging moves were introduced along with it itself or later. Fairy Wind, Disarming Voice, Dazzling Gleam, Moonblast, Play Rough... There's no real benefit to the Fairy Type right now.
That aside, I've got a bunch of things I feel I must bring to light.
The trade on Route 2 should actually be for a Mr. Mime. The Abra requirement is correct.
The traded Farfetch'd wasn't holding the Stick like it does in FRLG (not that I mind the Smoke Ball from the Dodrio trade you converted) and still had the Dodrio's name and OT. Just in case you're after greater accuracy.
The Bike Voucher, though programmed properly, doesn't show up in the Bag like it should. Oak's Parcel is also like this.
The Fishing Guru in Vermillion City does not give the player an Old Rod.
On the subject of Magikarp, There's no Salesman who'll sell one in the Route 4 Pokémon Centre.
There's still some Apricorn Trees in Pewter City. If that's intentional or not, I don't know, but not being able to get the Apricorn Box to put them in is annoying.
I find it weird that Professor Oak's Phone Number isn't in the player's Phone Registry, nor given to them by him to evaluate the Pokédex at the beginning of the game. Perhaps the Aide who gives you Flash can do if you talk to him afterwards or something?
Some encounters are bugged, No specie is determined and the wild Pokémon is at level 0. I've witnessed this on Route 5, Route 24 and Route 9. Other areas may be affected as well, but I have yet to see such an issue.
Certain Trainer names and dialogue are incorrect, Notably, the Team Rocket Grunt in Mt. Moon is listed as 'Team Rocket Toby' instead of 'Team Rocket Grunt'. While I love the idea of giving the nameless mooks of Team Rocket names. They can't be nameless if they have names. Additionally, some of the overworld sprites don't correlate to the corresponding trainer classes when battling various NPCs. An example of this is the first girl you see on Route 4. Her overworld sprite is an Aroma Lady but she is actually a Lass.
In-battle dialogue with the Rival and Gym Leaders treat you as if this is still HGSS. The Gym Leaders treat you like you're not from Kanto and Blue acts like Silver.
The Gym Guide who gives you advice is not in any of the Gyms for some reason.
After clearing the SS. Anne, Bill's PC doesn't display Eevee and its evolved forms. Additionally, after helping Bill out, the PCs in Pokémon Centres should have changed "Someone's PC" to "Bill's PC".
The Rocket Grunt that stole TM28 is nowhere to be seen. Since it's Dig, it'd go a long way to helping in the Vermillion Gym. Perhaps rescripting the Policeman to stand in the area leading south out of Cerulean and having event tiles that have him stop you from leaving that way to force you round the other way to encounter the Rocket Grunt and recover the TM.
There's a Battleable NPC that's missing from Route 24's Grass patch.
The ORAS menu icons are decent, but largely poorly coloured. Grovyle and Nidoran♀ are strong examples of this.
The capture tutorial shows the unused Player backsprite, rather than pulling your hair out trying to fix an issue, I suggest having them as the old man's granddaughter or grandson with the old man recommending that they show the player how to catch Pokémon.
Perhaps a small oversight, but TM70 being Flash is a slight problem. Since Flash is no longer a HM that means it can be deleted, which also means that Rock Tunnel can get ridiculously harder for some people by way of an oversight. For safety ourposes, might I recommend adding an NPC that can sell you the Flash TM right near Rock Tunnel? Perhaps in the Pokémon Centre with the Aide that gives you the Everstone for Catching 20 Pokémon?
All of these, and likely more are most likely known by you, but perhaps you've missed some. I don't know. Now, for the good things I have to say:
I'm super pumped about this hack.There's a few changes that you've made compared to the orignals it's based on but a carbon copy is just outright dull. Every remake has alterations in some places so I'd say it's great to be flexible about it.
Everything I've seen so far has impressed me, and given that I know it's a WIP with adjustments still needing to be made basically everywhere this is a great start.
Keep it up! I'm eager to see more!