S Rank: Reserved for Pokemon that are amazing in the BH metagame. These Pokemon are usually able to perform a variety of roles effectively, or can just do one extremely well. Their use has low risk involved and high reward exerted. Pokemon in this rank have very few flaws that are patched up by numerous positive traits.
S Rank
Chansey
Mega Diancie
Mega Rayquaza
Mega Mewtwo Y
A Rank: Reserved for Pokemon that are fantastic in the BH metagame, and can sweep, support, or wall significant portions of the metagame. These Pokemon require less support than most others to be used effectively and have few flaws that can easily be compensated for when compared to their positive traits.
A+ Rank
Mega Mewtwo X
Giratina
Mega Gengar
A Rank
Aegislash
Registeel
Mega Tyranitar
Mega Audino
Primal Groudon
A- Rank
Dialga
Shedinja
Mega Latias
Mega Latios
B Rank: Reserved for Pokemon that are great in the BH metagame. These Pokemon have more notable flaws than those above them that affect how they function in the tier. Their positive traits still outshine their negatives, but they require a bit more team support to bring out their full potential.
B+ Rank
Ho-oh
Arceus
Yveltal
Kyogre
Kyurem-Black
B Rank
Mega Gyarados
Regigigas
Slaking
Mega Slowbro
Mega Garchomp
B- Rank
Regirock
Xerneas
Mega Metagross
C Rank: Reserved for Pokemon that have notable niches in the BH metagame, but have just as many notable flaws that prevent them from being effective. Pokemon in the C tier often require significant support to be effective. Pokemon from this rank tend to face a lot of competition with the more commonly used Pokemon.
C+ Rank
Lugia
Mega Venusaur
Mega Sceptile
Deoxys-Attack
Mega Aggron
Mega Aerodactyl
Kyurem-White
Mega Blaziken
Cresselia
Mega Steelix
Gengar
C Rank
Palkia
Mega Scizor
Reshiram
Deoxys-Speed
Groudon
Hoopa-Unbound
C- Rank
Zekrom
Giratina-Origin
Mega Swampert
D Rank: Reserved for Pokemon that are mediocre in the BH metagame, but are viable enough to justify their use on select teams. These Pokemon are either usable but have no real niche, or are only capable of doing their specific task and fail at doing anything more than that. Pokemon from this rank have multiple crippling flaws that prevent them from being successful a majority of the time, and are often severely outclassed because of it.
D Rank
Mega Alakazam
Ferrothorn
Heatran
Mawile
Kangaskhan
Mega Heracross
Mega Salamence
Mega Ampharos
Pikachu
Nice job, this really needed doing at this point. I obviously have some noms, but hey.
-Heatran to unranked
Heatran has a niche, but it's not really a usable one. Its weak, lacks bulk, and wishes that thousand arrows didn't exist with a burning passion. Its even more one dimensional that anything else there. I suppose I can see it as not being useless, but I don't think we have to rank everything.
-Gengar to B-
While it does have the crippling flaw of manual evolution, shadow tag is amazing and it has no real competition from other mons that want to use the slot. While pivoting is pretty common, I think its still just to effective for the C ranks.
-Cresselia to C
The metagame isn't very good to it, and it isn't that bulky, especially considering its weakness to ghost, koff, and competition from Maudino. I'd even push for lower, really. If someone has a reason for it I'm fine, but much more usable mons are ranked lower down.
-Mega Audino to A+
This thing is amazing, even more so than the A tank. Its honestly one of the best mons ATM, as it has no common weaknesses, a great immunity, and some solid resistances, plus an incredible bulk. Will elaborate more later
what set is aegislash ranked for? it seems like registeel with worse bulk and the tiny niche of fighting immunity (but fighting isnt even a common attacking type)
Wail said it well, but I'm going to add on to what he said. Fighting immunity is great for MMX/Contrary in general, as well as close combat Megaray. With flash fire its one of the best imposterproofing out there, and can wall things like impostered MMY if they get caught as a fighting type, as well as imposterproofing boomburst for protean. Its basically a general utility typing, especially as Registeel loses to things like MGar and MMY anyway.