So I've looked at Fitzhogan11's Youtube playthrough of the game, and I've messed around with the latest download you've provided (I'm not gonna do a playthrough though, sorry). Here is my feedback/suggestions in no particular order, the whole purpose of this post is just to kind of describe what my vision for this was back in 2014.
* the level curve seems quite a bit higher than what I would have made it, it really seems to ramp up towards the end. But oh well, it's not like DarkViolet's level curve was balanced to begin with, it was already out of whack. And Fitzhogan11 still managed to beat the Lv70-80's Elite Four despite his team of Lv60's lol
* In general, for boss trainers like Elite Four and such, every Pokemon would have been the same level except for their signature Pokemon being two levels higher than the rest of the team (like how BW, B2W2 and ORAS does it, for example: Lv35, Lv35, Lv35, and Lv37. As opposed to a team of Lv34, Lv36, Lv35, Lv37). The final battles with Gym Leaders, Kamon, Giovanni, Elite Four and Champion should follow this rule as that is what I would have done.
* my original plan was that if you battled every trainer in Kanto (including the Elite Four), you would have seen all 210 Pokemon (minus the legendaries of course). Some Pokemon that the Elite Four use (such as Gengar, Machamp, Dragonite, etc.) would NOT have been used by normal trainers of course.
* glad to see that the cave layouts that were already in Beta 2 for Cerulean Cave and Victory Road made it in despite being inaccessible in Beta 2 lol
* on Fitzhogan11's videos, some trainers on the sea routes below Fuchsia use the wrong battle sprites, such as a Picknicker using the default FRLG sprite instead of the HGSS styled ones that it should use
* not to sound nitpicky but pretty much all of the added maps have tile errors and inconsistencies with the maps that were already in Beta 2. But the layouts are good though. I understand maybe you're relatively new to ROM hacking but maybe someone could help you with that (but not me lol, I'm done with ROM hacking)
* Seafoam Islands wasn't going to use the FRLG tileset, at some point before cancellation I actually made a tileset for it that looked like the HGSS one but in RSE style (like the rest of the maps). Shame I don't have it anymore though :(
* In your beta you can't actually reach Articuno. I see that you've mimicked the HGSS Seafoam Islands layout, which is great because that's exactly what I would have done, but it seems that you didn't account for the sliding ice block puzzle that HGSS did (I probably would have removed it or replaced it with Strength puzzle) and as a result you can't reach Articuno :(
* none of the new areas have proper door animations
* Pokemon Mansion would have looked a bit different than it does in FRLG. I never made tiles for it but like the other areas it would have just been gone by the "what would this place look like in RSE style" motto. I don't blame you for keeping the original FRLG tiles though, it gets the job done.
* The layout for Pokemon Mansion would have been mostly the same EXCEPT towards the deepest part, the diary would have been located in it's own little room and you would actually have battled Ariana and Archer one last time leading up to it.
* Birth Island looks a bit different from what I intended. I would have intended it to look EXACTLY like how it does in Emerald just for the sake of consistency, right down to the RSE rock palettes and the unique trees. It also needs its proper dock building (same with the postgame areas).
* Like Birth Island, I would have made Faraway Island look EXACTLY like it does in Emerald, including the really tall grass
* I know you're not a music hacker, but I might as well just say this anyways lol. Kamon and Giovanni would have had their own final battle themes that are more "intense" versions of their original themes
* Cerulean Cave was going to have its own unique theme, kind of a "final dungeon/this is it" vibe
* Mewtwo was going to have its own battle theme separate from the legendary birds theme. Mew was also going to use Mewtwo's battle theme (in Fitzhogan11's video you made it have RSE battle music?!?). However, I think using the theme I made for the legendary birds works just fine for Mewtwo and Mew.
* It was great seeing Fitzhogan11 do the Mewtwo vs Deoxys battle lol, leading up to that moment was kind of the whole point of DarkViolet. Although this version of DarkViolet was made from 2012-2014, I had worked on the mukty plot in 2011 when Black & White were the newest Pokemon games. So the whole idea was (badly) inspired by Black & White with it's Reshiram vs Zekrom moment, so I thought "let's do that but with Mewtwo and Deoxys" and then if Giovanni was going to play Ghetsis's role, we needed someone to do N's role so that's why "Kamon" (known by many as Silver) was thrown in there
* I would suggest switching around Mewtwo's level-up set so that it doesn't have Shadow Ball when you catch it, that way the battle with Deoxys is a bit harder. Also make sure Deoxys also has Psycho Boost. The idea was that Mewtwo and Deoxys would Psycho Boost each other lol.
* I like how you handled the Giovanni & Kamon scene on Route 22. Pretty much exactly how I would have done it.
* In general, I would not have had unevolved high-level wild Pokemon. For instance, rather than Lv50 Spearow's appearing on Route 23, they would have been Fearow's, period. Every Pokemon past its evolutionary level simply would have been its evolved form. (So yeah, feel free to add wild Pidgeots in the postgame areas lol)
* Route 23 would have used a remix of HGSS's Route 26-27 music (but ONLY Route 23. Indigo Plateau would have still used its original music albeit with its pitch corrected)
* the battle with Green/Red on Route 23 would have actually played a demix of the BW/B2W2 VGC Champion Battle theme, which itself is a remix of the RGBY Champion battle theme (I'm not kidding lol, this was always my plan)
* Indigo Plateau's music would have been the same as FRLG, just lowered in pitch to match RGBY
* Victory Road would have used a remix of its HGSS music
* Tauros would have been found on Route 23, and it would have been the only location its available in-game
* Dratini would have been found in the water on Route 23
* I would have put some Trainers in the lower portion of Route 23
* I love how you handled Moltres in Victory Road. To be honest I would have just shoved it in somewhere like how RGBY did it, but I like your idea better because it kind of keeps in spirit of what FRLG originally did with its little room in Mt. Ember.
* the Elite Four was going to have a brand new remix of the Kanto Gym Leader battle theme (also in Fitzhogan11's video, the victory theme plays the regular trainer victory theme instead of the Gym Leader victory theme that it should)
* the Champion was going to use its FRLG theme, but with its pitch lowered to match RGBY
* the Champion is supposed to have Machamp instead of Alakazam (I think you already fixed that though as someone pointed out, but in Fitzhogan11's video he uses Alakazam)
* when you beat the Champion, instead of playing the Gym Leader victory theme, I was going to have it play the title screen music. I'm not joking.
* I only had very vague ideas for the postgame areas, but what you made fits my ideas well. Obviously based on the map (which I'm glad you followed) the idea was to make some equivalent to Sinnoh's Battle Zone, which is what you did.
* As already mentioned, the new maps have a lot of tile errors and style inconsistencies, Battle Zone as well. The layouts are great but it just needs a bit more polish, that's all
* I would also suggest varying up the graphics a little in the Battle Zone so that not everywhere looks the same
* You used FRLG-style house exteriors in the Battle Zone, that is NOT something I would have done. One of DarkViolet's aspects was to use RSE-style graphics, including the houses, and that means the door heights as well.
* If you go to Celadon City and head to the balcony of the "Chaos Rush Headquarters" building (right next to the Game Freak building), there are a couple trainers that are actually cameos of ROM hackers giradialkia and MrDollSteak, who had helped me over the years. They were intended to be battle-able after you beat the Elite Four. I believe that their teams are already in the ROM in Beta 2, their flags just need to be activated so that you can battle them after you beat the Elite Four.
* Prof. Oak would have been battle-able after you beat the Elite Four. I never planned out his team but it would have been very similar, if not exactly the same as his RGBY beta team. Do whatever you want with that piece of information.
* Bulbasaur, Charmander, and Squirtle would have been obtainable in some way in the post game. I never thought of how though lol, so it's up to you to decide how you want to include them.
* in order to fix the tiles glitch with the Elite Four PokeMart, replace the tiles in the room with the ones from the top part of the main tileset.
* Blaine's Gym should have a DarkViolet-styled battle background, not a default FRLG battle background
* Same with the Elite Four and Champion, the backgrounds should be DarkViolet styled and not default FRLG. The Elite Four would have had their own colors for their battle backgrounds, of course.
* minor error with Deoxys's data, it's supposed to be genderless. This is my fault because in the data I had made a "new" Deoxys because the FireRed Deoxys is Attack-forme and I wanted Normal-forme for the story
Anyways, thank you for finishing this hack for me. I abandoned it because I was not pleased with some decisions I made and felt I had better ideas. Plus there were a lot of issues such as the ridiculous story that was a BW-rip off shoved into Kanto, grammar issues (in my defense English is not my first language but it's my best language so I'm in a weird situation with that), and a whacked-up level curve. Those were just some of many reasons why I canceled it, but I'm glad you went and finished it because you have no idea how many messages I've gotten in the past four years asking "when is the next beta coming out?" lol. Obviously things are slightly different than how I would have done it, but what you did is pretty damn close to my original vision and functions as a completed game, which should keep the fans happy. I hope that you'll consider the feedback that I've provided in order to make it even more like my original plan, but don't feel obliged to follow it exactly because I'm not exactly proud of what I worked on. If you have any questions about what my ideas were for certain things, feel free to ask and I'll do my best to answer them.
I'm assuming you'll continue to work on this to complete it more. If a future version comes that addresses the issues I've brought up in my feedback, I will update the first post to include the final version (don't worry about adding new music, I know it's easier said than done. I'm fine with Mewtwo using the bird theme, thought i would prefer that Mew uses the same theme Mewtwo does as well).
Again, thank you so much for doing this, hacksrepairman.