TL;DR: Dragonite and Tyranitar cannot be bad. Everything else can. Arcanine and Kingdra may improve a lot. Original spreadsheet here.

WARNING: There is a lot of speculation and guesswork here. At least guesses are data-based / educated guesses.

With the gym rework, there is an outside chance that the CP formula or the stats (or just the usefulness of each species) will change.

Therefore I analyzed the base stats of the original Pokémon games in order to guess how “robust” each species could be in case of a recalculation of stats/CP/ranking.

Methodology

Pokémon have 6 stats: HP, Attack, Special Attack, Defense, Special Defense, Speed.

In this spreadsheet I have ranked the top 10 Pokémon by different stats combinations:

Stats sum Stats product Sum of squares Best speedless Worst speedless Best product Worst product CP Lowest stat Tyranitar Dragonite Shuckle Blissey Tyranitar Blissey Dragonite Tyranitar Dragonite Dragonite Tyranitar Blissey Snorlax Lapras Dragonite Arcanine Dragonite Arcanine Arcanine Arcanine Tyranitar Rhydon Dragonite Gyarados Crobat Snorlax Meganium Blissey Kingdra Dragonite Tyranitar Arcanine Tyranitar Tyranitar Rhydon Venusaur Snorlax Typhlorizard Steelix Vaporeon Exeggutor Vaporeon Kingdra Gyarados Typhlorizard Gyarados Feraligatr Snorlax Donphan Kingdra Espeon Lapras Blissey Blastoise Kingdra Blastoise Cloyster Steelix Snorlax Jolteon Meganium Vaporeon Feraligatr Lapras Gyarados Arcanine Golem Meganium Alakazam Blastoise Donphan Golduck Crobat Crobat Gyarados Dragonite Blastoise Aerodactyl Typhlorizard Espeon Kingdra Typhlorizard Venusaur Lapras Gyarados Umbreon Miltank Starmie Exeggutor Nidoking Golem Nidoqueen

Stats sum = plain sum of all base stats (considering Physical and Special Attack/Defense as separate stats)

Stats product = plain product of all base stats (considering Physical and Special Attack/Defense as separate stats)

Sum of squares = sum of the squares of base stats (it tends to boost species with one or two very high stats)

Best speedless = product of Attack x Defense x HP, considering the maximum of Physical and Special for both Attack and Defense

Worst speedless = the same but considering the minimum

Best product = Attack x Defense x HP x Speed, considering the maximum of Physical and Special for both Attack and Defense

Worst product = the same but considering the minimum

CP = the current CP ranking

Lowest stat = the lowest base stat of all (it tends to boost species with balanced stats)

Some rankings may make no sense, but I have considered them all nevertheless, because Wynaut.

Then I calculated which Pokémon come in the top 3 or top 10 for how many combinations.

In addition I have ranked the top 10 by each single stat:

Top 10 HP Top 10 Att Top 10 SpAtt Top 10 Def Top 10 SpDef Top 10 Speed Blissey Tyranitar Alakazam Shuckle Shuckle Electrode Wobbuffet Dragonite Espeon Steelix Mantine Jolteon Snorlax Flareon Gengar Cloyster Blissey Crobat Wigglytuff Rhydon Exeggutor Forretress Umbreon Aerodactyl Lapras Machamp Magneton Skarmory Tentacruel Alakazam Vaporeon Scizor Ampharos Golem Hypno Dugtrio Lanturn Ursaring Omastar Omastar Hitmontop Starmie Muk Kingler Jynx Magcargo Slowking Sneasel Rhydon Gyarados Houndoom Weezing Hitmonchan Persian Tyranitar Pinsir Vileplume Donphan Snorlax Jumpluff Vaporeon Rhydon Flareon Espeon Jolteon Hitmonlee Raichu Ledian Gengar Dodrio

Then I have assigned 1 point for appearing in a Top 10, 1 additional point for appearing in a Top 3, and 3 points for appearing in two different Top 10 for single stats. Finally I have subtracted 30% (i.e. multiplied the final score by 0.7) for Pokémon with a double weakness.

Results

This is the final ranking (details are in the spreadsheet):

Rank # Ranked species Points 1 Dragonite 11.2 1 Tyranitar 11.2 3 Blissey 11 4 Arcanine 10 4 Snorlax 10 6 Vaporeon 6 7 Kingdra 5 7 Lapras 5 7 Espeon 5 7 Shuckle 5 11 Gyarados 4.9 12 Rhydon 4.2 13 Blastoise 4 13 Typhlosion 4 13 Crobat 4 13 Meganium 4 13 Jolteon 4 13 Alakazam 4 19 Flareon 3 20 Charizard 2.8 21 Omastar 2.1 22 Donphan 2 22 Feraligatr 2 22 Steelix 2 22 Venusaur 2 26 Exeggutor 1.4 26 Golem 1.4 28 Miltank 1 28 Cloyster 1 28 Starmie 1 28 Aerodactyl 1 28 Golduck 1 28 Nidoqueen 1 28 Nidoking 1 28 Umbreon 1

Disclaimers