Alright, champion defeated, nuzlocke failed, most stuff done, here are the things I noted.
Brock seems a bit too hard, kudamon specifically is almost impossible to counter with the digimon you have access to before him, between it's typing, ability and coverage, and grinding is super slow because of the low exp yealds although, those are almost the same as the original.
The rockets are mostly well balanced but sukamon with revenge so early almost 100% going to kill at least one your mons, not necessarily a problem, just salty it took my metal-koromon XD.
Some exp yields are definitely too low, specifically babies and in-trainings, which would not be a problem, except for the fact that even high level trainers have some of them, making the fights feel less rewarding, also some perfects and megas give very little.
The two unskippable trainers right above vermillion, if you vs seeker the girl she will have a lv18 vikemon, I presume that's not intended but being low level and having very weak moves it's not a big gameplay problem, great exp though.
The boy right below her, if vs seeker battled has a lv 21 metalgarurumon AND weregarurumon, again, low level and weak moves don't make him insurmountable, but the metalgarurumon specifically is bulky as hell that early, good thing I had dragon rage :D, again great exp, they don't have them after a couple badges though, no idea why. After Erika, two trainers on nugget bridge have vikemon and Ophanimon, but they are so low level that it doesn't even count.
Several other occurrences of random megas in remetch teams, probably the team building coding, they look scary but all in all are not that big a problem.
When my weedmon evolved into blossomon at lv 40, the resulting blossomon was lv 42 instead, surely somethign to do with the exp curve of the two.
Seadramon, betamon, darktyrannomon, k.numemon, pandamon, shoutmon sword, seems to be uncatchable, ultraballs don't even shake once at 1 hp, masterball works.
Seasarmon is in place of articuno instead of Neptunemon.
The game freezes when roost is used by enemies, don't know about allies.
In the pokmon mansion, in the room with the max potion and the book about lucemon's ritual is a burglar that will freeze the game if talked to, if you fight him he has a lv0 missingno and still freezes the game.
Plesiomon only has 1 hp, I'm guessing it took shedinja's place and it's programming is still there.
lavogaritamon evolves into itself every level and does not evolve into Volcanicdramon.
Leomon has incredibly low attack.
Moonblast has 40pp.
Also, I couldn't find the itemfinder, possibly because of the changed rewards from the aides (great Idea by the way, that everstone was always useless in hacks).
That is all, I had a ridiculous amount of fun replaying it whit so many changes, I how this information helps you :D.
Now, a couple considerations I havo to make give my experience with the game.
During the whole game exp earned felt too low with how much higher the levels of enemies are, may I suggest adding a lucky egg somewhere near the beginning, putting the expshare earlier, or maybe putting rare candies in the coinshop?
I still feel that lv 100 for the ultras is a bit much but eh, I'll complete the dex in this one too as soon as it's possible because I'm having just this much fun XD.
Are the sevii islands 4-9 closed because you want to do something with them or you just didn't want them playable? If so why? Being able to go into cerulean cave without doing them is great though.
Crabmon being the only catchable thing it almost all non sea water point makes me sad , so many lost encounters :(.
Last but not leas, I feel like it could be cool being able to find the type boosting items somewhere, they were very scarce in FR/LG.
That is all thanks again for this awesome experience :D.