Latios & Latias: A+ >>>> S- Rank
Despite the ubiquity of bulky steel-types, Lati@s still maintain a top spot in the metagame. In fact, the rationale for having steels on almost all bulky/balanced teams is because of the presence of these Pokemon. They are actually quite diverse, being able to stallbreak effectively with Calm Mind and even cheese teams with Healing Wish or Memento. And, of course, the ubiquitous Defog set gives several teams a way to use an offensive Arceus-Forme. With moves like Hidden Power Fire, Lati@s can effectively circumvent certain checks and counters, and being able to check both Primal Pokemon fairly well, they are very splashable in several teams. Modest Lati@s hit extremely hard, and very well can break even the most well built of teams. - dice
Arceus-Ghost: A+ >>>> S- Rank
Arceus-Ghost is still the best non-Normal Arceus Forme. The resurgence of Lati@s gives it another Pokemon to check, not to forget that it also is an effectively counter measure to several other Psychic-types in the tier. Checking non-Refresh Arceus-Normal (or using Focus Blast) is also a major boon. Also, Arceus-Ghost is one of the few Arceus-Formes which cannot be threatened by Wobbuffet's presence. Swords Dance Arceus-Ghost is also a very underrated and threatening Offensive Sweeper. It is actually quite diverse, and you can't know which set it is running when its sent out; Swords Dance and Calm Mind have very different sets of checks and counters. This Pokemon is most definitely deserving of S-. - dice
Primal Kyogre: A+ >>>> S- Rank
If a Primal Kyogre switches into your Primal Groudon, you know something bad is going to happen. This Pokemon can overpower even Lati@s and effectively as a check to Primal Groudon with a physically defensive set and CM Arceus with a specially defensive set. It has quite a few tools in its kit, and this Pokemon is vastly underrated next to Primal Groudon. Although you have to be careful about Groudon coming into it, Primal Kyogre can tear apart teams with meticulous play and smart teambuilding. - dice
Klefki: A >>>> A+ Rank
Klefki is, quite simply, the best Spike-user and most splashable Steel-type in the metagame. Being able to threaten common Defog-users such as Lati@s and Giratina-O, and having access to Toxic for Defensive Arceus make Klefki a reliable hazard-setter. Although Diancie and Sableye may not be the most fun opponents to face, the fact that Klefki is a catch-all check and counter to Darkrai, Xerneas, Yvetal, and Lati@s, just to name a few, cements this Pokemon in A+. - dice
Mega Gengar: S- >>>> A+ Rank
Shadow Tag is most definitely a major threat in the metagame, Gengar's major downfall arises in its major opportunity cost to Salamence, comparatively speaking. Being a worse check to Arceus-Normal and lacking the offensive prowess that Salamence provides, Gengar has to be on a team which can take advantage of the specialization Gengar provides. Quite simply, Gengar is simply overshadowed by Salamence in 8.5/10 teams, making it have to drop. - dice
Arceus-Ground: A- >>>> A Rank
Arceus-Ground is the only Arceus-Forme which reliably checks Primal Groudon. This is reason enough to move it up to A-Rank. - dice
Arceus-Dark: A+ >>>> A Rank
Arceus-Dark's best niche is as a stallbreaker which sadly is almost nonexistent in the metagame. On balance as a CM Arceus-Ghost answer, Ho-Oh (and Yveltal to an extent) is far more splashable, while on Stall, Blissey and Kyogre are the go-to answers. This Pokemon, of course, has a unique niche in also providing a Mewtwo check, but from anecdotal experience, this metagame is just not suited for Arceus-Dark as well as the above Arceus-Formes. It's still fantastic for sure, but lacks the luster that Ghost and Normal have. - dice
Yveltal: A+ >>>> A Rank
While Yveltal has undoubtedly strong attacks, its far too easily checked by Fairy-types to be worthy of A+ rank. Teams that Yveltal fit on usually use the Phys Def set, and even that falls flat to many physical threats to be very useful.
Arceus-Water: B+ >>>> A- Rank
It's one of the few Arceus-Formes that can check Salamence. Also, Arceus-Water matches up somewhat well against Kyogre and is a cockblock to Ho-Oh. Primal Groudon can't stop this Pokemon when it's neutral to Ground-STAB and can Toxic. The common Stealth Rock set loses to this Pokemon 1v1. - dice
Deoxys-S: B+ >>>> A- Rank
Still as useful as a hazards lead as ever, and has the movepool to get around Magic Bouncers and Defog users if needed. Its very difficult to stop Deoxys-S doing its job, and not many teams have ways to anti-lead it.
Groudon: B+ >>>> A- Rank
Groudon is the most viable Primal Groudon check that can effectively set Stealth Rock. It also provides other boons as well-- the permanent Sun gives Ho-Oh free reign which not even Primal Groudon can provide. Also, it can also run an item like Lum Berry to lead against even Darkrai and still ensure Stealth Rock. On most teams, Primal Groudon is the best option, but Regular Groudon is most certainly a viable option to look out for. Primal Kyogre's seemingly underused status as of now makes this Pokemon even more viable. - dice
Ferrothorn: B+ >>>> A- Rank
Serves as a great blanket check to a number of threats, and is generally annoying with Leech Seed and Spikes.
Mega Sableye: B+ >>>> A- Rank
Magic Bounce is an extremely strong ability, and Sableye makes fantastic use of it. With a typing only weak to Fairy, Sableye can is hardly ever OHKO'd allowing it to annoy even the worst of matchups. Its typing also effectively allows Sableye to be fantastic switches to Mewtwo and Arceus-Normal, two major threats in the metagame. Foul Play also dissuades set up on this Pokemon. Due to Magic Bounce making Taunt unnecessary, Sableye's last move slot is flexible as well-- Sucker Punch, Toxic, Knock Off, and even Metal Burst are viable choices. This Pokemon is a fantastic answer to Suicide Spikes and has a strong defensive niche. - dice
Wobbuffet: B >>>> A- Rank
Much like Forretress below, this Pokemon also gained viability with the introduction of Custap Berry. It can defensive check Mewtwo on offensive teams, and give the most dangerous set up sweepers in the tier like Salamence and Primal Groudon a free turn of set up. Its team supporting capabilities makes it a godsend on more offensively inclined squads, and is quite dangerous against many matchups. Its presence against certain Pokemon simply dissuades the opponent from sending them out, giving the Wobbuffet user an inherent advantage from the team preview. - dice
Tyranitar: B+ >>>> A- Rank
As seen by its usage in SPL, this Pokemon is actually quite legit in ORAS. Although Primal Groudon is a thorn in its side, the ability to Pursuit-trap the omnipresent Lati@s and check Salamence with Shuca Berry give Tyranitar a unique niche. With Excadrill being able to hit Groudon super effectively, Sand as a playstyle actually gained viability. - dice
Forretress: C >>>> B+ Rank
Forretress is the go-to suicide Spiker with the introduction of Custap Berry with its access to both Toxic Spikes and Spikes and ability to 'Defog-Block' with Explosion. It also matches up well against the standard Deoxys-S set. With its Sand immunity, it is more reliable than the other suicide Spike leads and deserves a move up. - dice
Excadrill: B >>>> B+ Rank
As mentioned above, Excadrill's ability to hit Primal Groudon effectively made sand a more viable playstyle. Additionally, the ability to check Lati@s, Xerneas, and other fastmons allow Excadrill to pose a threat to Offensive teams which run rampant in the metagame. - dice
Skarmory: B >>>> B+ Rank
A nifty Salamence check and Spike user, Skarmory found its beak in the spotlight yet again. Although Lati@s can sometimes cheese even Specially Defensive sets with Calm Mind or Hidden Power Fire, its still a pretty reliable Pokemon with its ability to check most Physical attackers and phaze. It even can OHKO Diancie with Iron Head making it a more reliable Spike user than even Klefki.
It is, however, a free switch in to many threatening Pokemon like Primal Groudon and Kyogre which is why it's ranked much lower than its Fairy comrade. - dice
Mega Scizor: A- >>>> B Rank
It can't Defog on the most common Stealth Rock user. It can check Lati@s and Arceus-Normal still, but a free switch-in to Primal Groudon makes it a mediocre option on most teams. - dice
Mega Aerodactyl: C+ >>>> B Rank
As a Stealth Rock user for offensive teams which checks Ho-Oh, Salamence, and Arceus-Normal, it has a valuable niche. Additionally, it outspeeds all Arceus formes and thus Lati@s which allows it to keep Stealth Rock up. The newborn ForreAero core manifests the power of this Pokemon. -dice
Mega Blaziken: B+ >>>> B Rank
The new ORAS mons appear to have driven Blaziken into obscurity, and its not hard to understand why. Blaziken's STABs are easily resisted by common threats in Salamence, Ho-Oh, Giratina-O and the Latis. Blaze can still run coverage to hit them however, and its ability to act as a pseudo scarf mon in a slow metagame can work for some teams, its just that compared to XY Blaziken, it has fallen a long way.
Arceus-Grass: C+ >>>> B Rank
If Primal Kyogre goes up in viability, so do its checks. Arceus-Grass is no exception. Its ability to counter Groundceus is also a big bonus, and Grass Knot still hits Groudon for heavy damage.
Gliscor: B+ >>>> B- Rank
With Primal Groudon able to run special sets, Gliscor runs out of things to check, and is harder to justify on a team.
Palkia: B+ >>>> B Rank
Palkia's offensive abilities have not changed, but the lack of a defensive niche really lets it down.
Mega Metagross: C+ >>>> B- Rank
"basically its an offensive lati/xern check that doesnt give fires free switchins" - fireburn
Landorus-T: B >>>> B- Rank
Same reasons as Gliscor, really.
Mega Kangaskhan: B+ >>>> B- Rank
Kangaskhan's matchup vs HO is still very good, and it can heavily pressure teams with Spikes up. Its problem is that outside of the HO matchup, it doesnt have much else going for it.
Arceus-Electric: C >>>> C+ Rank
If Iceceus moves up, its only right that Eleceus does as well. Eleceus can still soft check birds, but the weakness to Primal Groudon and the non-STAB Ice Beam still hurts it from going any higher.
Arceus-Ice: C >>>> C+ Rank
With Ice being a great STAB in the current meta, and its ability to check Yveltal + Mence means its only right that it moves up.
Arceus-Flying: C- >>>> C Rank
Flying Arceus isnt the worst Pokemon out there, as Flying STAB is proving to be very good in this meta (see: ray, mence). It may be hard to justify over either of the two previously mentioned, but it can still work as a "Special Salamence" in very niche situations, and is also bulkier than Salamence in exchange for some resists and the lack of a mega stone.
Hippowdon: C >>>> Unranked (rejected for analysis)
Smeargle: C >>>> Unranked
Sticky Webs is an unviable playstyle, and Smashpass is as gimmicky as ever. See ya!
Ditto: C+ >>>> C-
Does well versus HO and general setup mons, but is more of a band-aid for lazy teams than a viable Pokemon.
Mega Slowbro: C >>>> C-
A fairly niche mon that has trouble checking Salamence even with 180 Defense. Still checks Primal Groudon however.
Tentacruel: C+ >>>> C-
Primal Groudon exists. Need i say more?
Mega Mawile: C- >>>> D Rank
I have no idea why anyone would ever use this.
that's all folks!