This is a really cool team! Since its an RMT, I'd be happy to give some advice on things I'd change or do differently. I'll go in order of the Pokemon listed.
Gyarados-Mega
- Firstly, replace Crabhammer with Foul Play. It still OHKOes a boosted Primal Groudon
and Mega Rayquaza:
+2 252+ Atk Gyarados-Mega Foul Play vs. -1 240 HP / 0 Def Groudon-Primal: 433-511 (107.9 - 127.4%) --
guaranteed OHKO
+2 0- Atk Gyarados-Mega Foul Play vs. -1 64 HP / 0 Def Rayquaza-Mega: 462-544 (125.8 - 148.2%) --
guaranteed OHKO
It also had the benefit of ignoring potential King's Shield drops from Primal Groudon.
- Potentially rework EVs. This is optional, but slight optimizations can be made based on what you want to live. If you prefer checking Primal Groudon, or certain Mega Rayquaza variants, you could tweak the EV spread to suit that role better. Below, I have given a table of some EV spreads worth looking into.
View attachment 571721
Oh, and be sure to minimize the speed on Mega Gyarados. This is to prevent some situations where you click Aromatherapy and gets hit with status in the same turn. Realistically it'll almost never happen but eh there's no relevant cost as far as I'm aware so you might as well make the tiny change if it could potentially help.
- You could also alter the moveset a bit. Aromatherapy and Poison Heal kind of have an anti-synergy to them. Defog could also not be ideal, as Mega Gyarados cannot be switched in to a general attack as well as most Wonder Guard clerics can, meaning it will realistically be more difficult to remove hazards. My suggestion is to remove Mega Sableye and replace it with a more traditional Wonder Guard cleric to free up these moveslots, so you can run things like Taunt, Spikes/Stealth Rock, Roost, or other support moves. Roost in particular would be very nice, since it lets Mega Gyarados not get worn down over time. It's a good check to Primal Groudon for example, but it needs to heal back to full every time in order to do so. Roost helps with that, so you aren't completely reliant on Poison Heal recovery.
Registeel
Overall, this Pokemon does pretty well as the defensive backbone of the team from the few games I've played with it. I was expecting it to be wors,e but it actually ended up working quite well, especially with Mega Gyarados to help with its weakness to Primal Groudon. I also think that Shed Shell would be a better item then Leftovers, here. Registeel is weak to a lot of common moves that Shadow Tag Pokemon Run, like Searing Shot/V-Create, Thousand Arrows, Close Combat, etc. And as mentioned, Registeel is kind of the defensive backbone of the team. If it gets taken out, then the team is on a very short timer, since it isn't exactly offense-oriented itself. You could also consider replacing Perish Song for something like Toxic. The only time I'd typically prefer Perish Song is when I'm playing against substitute, but the team already has decent answers for that. You could also use Whirlwind on Registeel over Stealth Rock, and move that to Xerneas
Regigigas
I only have two things to say. Firstly, I'd recommend running Silk Scarf or Life Orb instead of Safety Goggles. You have a Magic Bounce user and two Pokemon who are immune to status because of their Posion/Burn. You have plenty of insurance against Spore users, and Shadow Tag Regigigas desperately needs Silk Scarf or Life Orb in order to actually trap some Pokemon. Mega Rayquaza, Mega Mewtwo X, and even some variants of Mega Mewtwo Y need boosting items in order for you to KO them from full, which is very important. Additionally, the EV spread is wonky. It's better invest in max HP than to split up 128 in Def and 128 in SpDef.
Xerneas
- First, I think Safety Goggles should be changed out for Leftovers, for similar reasoning to Regigigas. Xerneas really appreciates the Leftovers recovery when it has Substitute.
- Wish is interesting, but I personally found it difficult to use along with sub. When opponents are very focused on countering, preparing for, and positioning around your substitute passing, I find it difficult to find turns to use Wish effectively, especially since Xerneas has no protection move. I personally think moves like Toxic Spikes, Minimize, Shell Smash, Stealth Rock, Taunt, or Spore would work very well. Xerneas' forth moveslot is very flexible.
- More EV spread tuning. Once again optional, but its worth looking into other EV spreads to help optimize your matchups against certain Pokemon. Here's another spreadsheet (the + next to a move means the Pokemon using that move has a nature that boosts that attack):
View attachment 571937
Unfortunately, this spreadsheet does not have information on the damage that Xerneas can do back to these Pokemon with Moonblast. Maybe I'll make a more comprehensive sheet in the future.
Sableye-Mega
I don't think this Pokemon works very well on this team, because it forces other Pokemon (specifically Mega Gyarados) to run moves they kinda don't want to. Additionally, it only adds to the Fairy weaknesses on the team which makes things like Diancie, Xerneas, and the occasional Mega Gardevoir very threatening. I think replacing it with a more traditional cleric to free up moves on Mega Gyarados and potentially Registeel and Xerneas would be nice. If you want to use Wish, Pokemon like Slaking, Blissey, or Primal Kyogre would work well. I reccomend Kyogre because it does the best job of staving off your weakness to coverage spam pokemon like Huge Power MMX or Protean Mega Latios.
Rayquaza-Mega
- Adamant Nature. There are a trillion rolls where you prefer Adamant over Jolly. Helps for Mega Gyarados, Xerneas, Giratina ... just use Adamant
- Maybe add something to hit Giratina. Trick does a great job of dealing with it, but comes with the obvious drawback of, well .... losing your Choice Band. Which kinda sucks. Something like Spacial Rend over Parting Shot or Extreme Speed could work. If you want to get really spicy, run Trick + Shell Smash so you can boost your stats after you neutralize Giratina. No idea how it would perform since I haven't used it, but it's an interesting idea to try out.
Overall, I like this team! It's pretty unique and uses some sets you don't see super often, which I enjoy. It ended up being better than I expected when I went to test it out, which was a pleasant surprise. Hopefully my advice can help make it even better!
RBY Hackmons Viability Rankings
Electrode
Everything Else
Electrode
Aerodactyl
Chansey
Gengar
Eiscue: B+ to A-
Articuno: UR to B
Urshifu: UR to B
Zapdos: UR to B
Zarude: C- to B-
Indeedee: UR to B-
Celesteela: UR to C
Crobat: UR to C
Darmanitan-Galar-Zen: UR to C
Zamazenta-Crowned: UR to C
Zeraora: UR to C
Regieleki: S+ to S
Cramorant-Gorging: S to S-
Zacian-Crowned: S- to A+
Calyrex-Shadow: A+ to A-
Regigigas: A- to B+
Grimmsnarl: A- to B
Rayquaza: B to B-
Aegislash: A- to C
Obstagoon: A- to C
Corviknight: B to C
Necrozma-Dawn-Wings: B to C
Mewtwo: B- to C
Mimikyu: B- to C
Reshiram: B- to C
Dragapult: C+ to C
Doublade: A- to UR
Drapion: B to UR
Gyarados: C+ to UR
Braviary: C to UR
Gourgeist-Super: C to UR
Hydreigon: C- to UR
Krookodile: C- to UR
