S Rank
Gyarados-Mega [Wins against both sets]
Tapu Koko [ROF, banned]
[0/1]
A+ Rank
Charizard-Mega-X [Beat by both Stored Power and Choice Specs set] (1)
Dragonite[Beat by Stored Power set, not by Choice Specs tho] (2)
Magearna [Flimsily countered by Choice Specs, more reliably countered by Stored Power set] (3)
Metagross-Mega [Countered by both sets] (4)
Mimikyu [TWaveCurseKyu counters Necrozma, but otherwise Choice Specs should counter Mimikyu] (5)
[5/5]
A Rank
Charizard-Mega-Y [Both sets lose since Mega Charizard-Y outspeeds and KOs]
Landorus-Therian [Choice Specs match-up is prediction based on Sub/not Sub on Landorus-T, but Stored Power counters more reliably] (6)
Snorlax [Luck based for Stored Power set, no chance for Choice Specs set unless turn 1 wake]
Tapu Lele [Beat by Stored Power set, wins Choice Specs] (7)
Zygarde-Complete [Beat by both sets] (8)
[3/5]
A- Rank
Aegislash [Beats Choice Specs set, Stored Power wins unless Aegislash has Metal Sound] (9)
Genesect [Choice Specs loses, Stored Power set wins] (10)
Lopunny-Mega[Beat by both sets,
unless Lopunny doesn't Mega, and uses Laser Focus] (11)
Magnezone[Metal Sound and Mirror Coat exists, so both sets get countered by Magnezone]
Mawile-Mega [Both sets wins, with Choice Specs based on a roll in favor of Necrozma] (12)
Porygon-Z [PZ beats Choice Specs Necrozma, loses to Stored Power sets unless Dark-type Z-Conversion] (13)
Slowbro-Mega[Beat by Stored Power set, not by Choice Specs set] (14)
Venusaur-Mega[Beat by both sets] (15)
[7/8]
B+ Rank
Aggron-Mega [Beat by Choice Specs set] (16)
Blaziken [Beat by both sets] (17)
Donphan [Beat by both sets] (18)
Gardevoir-Mega [Beat by Stored Power set, unless Disable-Encore] (19)
Golem [Beat by both sets] (20)
Greninja [Beat by Choice Specs set, wins against Stored Power] (21)
Jumpluff [Wins against both sets, unless Sleep Powder misses]
Naganadel [Beat by both sets] (22)
Pinsir-Mega [Beat by both sets] (23)
Primarina [Beat by Stored Power set, wins against Choice Specs] (24)
Tapu Fini [Beat by Stored Power set unless Taunt, loses to Choice Specs]
[9/11]
B Rank
Altaria-Mega [Beat by both sets] (25)
Chansey [Wins against both sets]
Ferrothorn [Beat by both sets] (26)
Garchomp [Necrozma can win if it predicts Choice Band vs ZChomp for Choice Specs set{on whether to use Photon Geyser or not}, and beat by Stored Power set] (27)
Heatran [Beat by Stored Power set, wins against Choice Specs] (28)
Heracross-Mega [Beat by both sets] (29)
Kartana [Beat by both sets] (30)
Meloetta [Wins against both sets]
Mew[Wins against both sets]
Necrozma [No comments]
Sableye-Mega [Wins against both sets]
Sawk [Beat by both sets] (31)
Tyranitar-Mega [Wins against both sets]
[7/13]
B- Rank
Blastoise-Mega [Beat by both sets] (32)
Blissey [Wins against both sets]
Buzzwole [Beat by both sets] (33)
Celesteela [Beat by Stored Power set, wins against Choice Specs] (34)
Crustle [Beat by both sets] (35)
Diancie-Mega [Beat by both sets] (36)
Durant [Beat by both sets] (37)
Gengar-Mega [Wins against both sets]
Hoopa-Unbound[Wins against Stored Power set, beat by Choice Specs] (38)
Kommo-o [Beat by both sets] (39)
Swampert-Mega [Beat by both sets] (40)
Togekiss [Beat by both sets] (41)
Whimsicott [Wins against both sets]
[10/13]
C+ Rank
Archeops [31.3% chance to win against Stored Power, no chance of winning against Choice Specs] (42)
Avalugg [Beat by both sets] (43)
Camerupt-Mega [Beat by Stored Power, wins against Choice Specs] (44)
Carracosta [Beat by both sets] (45)
Excadrill [Beat by both sets] (46)
Gallade-Mega [Beat by both sets, unless Disable-Encore] (47)
Latios [Wins against both sets]
Lucario-Mega [Beat by both sets] (48)
Marowak-Alola [Beat by both sets] (49)
Medicham-Mega [Beat by both sets] (50)
Pheromosa [Beat by Stored Power, wins against Choice Specs] (51)
Porygon2 [Wins against Choice Specs, beat by Stored Power] (52)
Scizor-Mega [Beat by Choice Specs, loses to Stored Power because Bug Bite eats Sitrus Berry Away ;-;] (53)
Tapu Bulu [Wins against both sets]
Terrakion [Beat by both sets] (54)
Umbreon [Wins against both sets]
Victini [Beat by Stored Power set] (55)
Volcarona [Wins against both sets]
[14/18]
C Rank
Blacephalon [Wins against both sets]
Deoxys-S [Wins against both sets]
Entei [Beat by both sets] (56)
Garchomp-Mega [Beat by Stored Power set] (57)
Haxorus [Beat by both sets] (58)
Hydreigon [Wins against both sets]
Infernape [Beat by both sets] (59)
Keldeo [Beat by both sets] (60)
Landorus [Both sets win, Choice Specs set win based on prediction of Sub/no Sub]
Latias-Mega [Wins against both sets]
Nihilego [Between Sub and Acid Spray, wins against both sets]
Ninetales-Alola [Wins against both sets]
Pidgeot-Mega [Beat by both sets] (61)
Relicanth [Beat by both sets] (62)
Thundurus-Therian [Beat by both sets] (63)
[6/15]
C-Rank
Hitmonlee [Beat by both sets] (64)
Manectric-Mega [Beat by both sets] (65)
Pyukumuku [Wins against both sets]
Quagsire [Wins against both sets]
Rhyperior {Beat by Stored Power set, wins against Choice Specs
Serperior [Wins against both sets]
Salazzle [Beat by both set, unless Disable-Encore, which is the most used strat]
Skarmory [Beat by both sets] (66)
Stakataka [Beat by both sets] (67)
Suicune [Wins against both sets]
[4/10]
D Rank
Abomasnow-Mega [Beat by both sets] (68)
Alakazam-Mega [Wins against both sets]
Aron [Beat by Choice Specs, wins against Stored Power] (69)
Azumarill [Beat by both sets] (70)
Barbaracle [Beat by both sets] (71)
Clefable [50/50s vs Choice Specs, wins against Stored Power]
Dusclops [Wins against Choice Specs, beat by Stored Power] (72)
Sceptile [Beat by both sets] (73)
Slaking [Beat by both sets] (74)
Smeargle [Wins against both sets, unless turn1 wake]
Stunfisk [Beat by both sets] (75)
Type: Null [Wins against both sets]
Vivillon [Wins against both sets]
Volcanion [Beat by both sets] (76)
[8/14]