S Rank: Reserved for Pokemon that are the pinnacle of the BL0 metagame. These Pokemon are able to perform a variety of roles very 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. These Pokemon define the metagame.
Arceus-Fire Giratina-O Genesect
A Rank: Reserved for Pokemon that are fantastic in the BL0 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. These Pokemon exert a strong presence in the metagame.
Arceus-Bug Charizard-Mega X Deoxys-N Mawile-Mega Sableye-Mega Scizor-Mega
B Rank: Reserved for Pokemon that are great in the BL0 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. These Pokemon exert an above average presence in the metagame.
Arceus-Grass Charizard-Mega Y Jirachi Keldeo Kyurem-B Latias-Mega Manaphy Slowbro Tyranitar
C Rank: Reserved for Pokemon that are mediocre in the BL0 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. These Pokemon exert a below average presence in the metagame.
D Rank: Reserved for Pokemon that are highly mediocre in the BL0 metagame, but are viable enough to justify their use on select teams. These Pokemon 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. These Pokemon exert a poor presence in the metagame.
Blissey Breloom Hoopa Latios-Mega Sableye
Undetermined Rank: Reserved for Pokémon that have yet to have a rank determined. This does not mean that any of these Pokémon are bad in any way, just that we have not had time to make the correct decision on the placement.
All OU and below Pokémon that have actual viability.
*Unless a special circumstance, nothing on this list is a final decision.*