Draining Kiss worked fine for me. It was one of my Jynx's moves at a certain point. Oh, and on the Draining Kiss note: the original Draining Kiss had only 50 base power, and 75% recovery, but the Draining Kiss inside Emerald Omega is like a Giga Drain: 75 base power, 50% absorption, still recovering the same amount but dealing more damage.
About the new abilities, i don't think we should implement more tbh. Since the beginning, Moxie Salamence for example was too strong in gen V, and with the lack of Choice Scarf, Life Orb, Focus Sash, Custap Berry or even Eviolite inside this mod, the number of things that can stop Salamence from sweeping is extremely limited (the most viable ones i found so far are Starmie (which will lose against Dragon Dance Salamence), Froslass (which is normally a lead anyway), Mamowine (which will lose if Salamence has a Dragon Dance and is at full health), or some bulky walls like Skarmory (and even then Salamence mostly runs Fire Blast in the Smogon sets, which this mod is based on)).
I do have a few suggestions though. First, the OP should change Wish's mechanic to fit with gen V/VI. To begin with, only Vaporeon/Umbreon/Chansey are useful Wish passers, and only the former has the ability to safely pass Wishes through Baton Pass, but the fact that Wish will only recover 1/2 of the recipient's health makes them unworthy at times. And then, this mod lacks one of the most influential moves in Pokemon: Stealth Rock. The only EH in this hack is Spikes, which can be easily be bypassed by Flying types or Levitate, while being extremely tedious to set up (wasting 3 turns to reach its max damage of 25%). I agree with the SandStorm part though. In addition, team building in this mod is much harder than normal since many Pokemons do not have their usual checks. For powerful Dragon types like Salamence/Garchomp, Starmie seems to be the only option (although Togekiss can still check them decently (provided that they both do not have Stone Edge)) alongside Swampert. For bulky Water types like Swampert himself, i found phazing them to be the only way besides wasting a team slot on a Grass type, making Vaporeon the most useful choice since it also has Wish and Protect (which helps a lot against defensive Gyarados). And this maybe a weird idea, but you can make Record mixing available between at least 2 Emerald Omega roms. Record mixing was a good way to EV-train, but it's impossible currently. And like i said before, the OP can try to implement more useful items like Choice Specs, Choice Scarf, Life Orbs, etc, since they form a big part in many offensive Pokemons, especially Life Orb. Eviolite can be implemented to give us a more all-around wall like Porygon-2. Another thing, i wish that we can re-battle Steven and Red, since they were actually challenging somewhat (Red was unlucky enough to keep using Thunder Wave on my Swords Dance Garchomp so yeah).
For your suggestion on the level curve, i think it's fine as it is. Before reaching the 8th gym, my Jynx was already at level 100, while the other Trainers managed to send my Toxicroak to level 90, meaning that if you divide the battles carefully, you will be able to get at least a team of 4 Pokemons all at levels near 70. This hack makes us think before over-leveling our Pokemons. The one thing i do wish to add though, is that this hack makes EV training BEFORE the E4 extremely complicated. For examples, the usual Atk training place, which is that Ghost Tower, now also have Gastly and Duskull infested in them, lowering your rate of EV-train. Spd can still be trained by Surfing and battling Gol/Zubats, so it's ok, but HP is a different story. The only viable place for HP before E4 is Victory Road, which has Makuhita/Hariyama, but even then their total chances of meeting was only about 30-40%. After the E4 it's much easier to EV train since you can use the Ditto trick, but i still wish for the OP to modify a few locations to make them more suitable for EV-training.
The perfect IVs part is a good idea, but only on paper. If you want to implement that, you need an indication of perfect IVs the moment you enter the battle, since after you have captured a Pokemon, you can just fly to Battle Tower and let the old guy check for you. Tbh, even though i dislike IV-training, i still managed to get decent IVs through mass-breeding. Catch a bunch of needed parents, choose out the best male, filter out the best female, breed for a bunch of eggs, then choose the best child from that. Using this method, i managed to get Garchomp with 29 IVs Atk (tested at Lv 100), Gyarados with 30 IVs Hp, 24 Def, 26 Sp.Def.