In Pokemon GO, the strength of a Pokemon is determined by its Combat Power (CP). Although there are many factors, including the strengths and weaknesses of a Pokemon that determine the outcome of any battle in the game, Pokemon with a high CP are generally considered strong Pokemon.
Top 5 strongest Pokemon in Pokemon GO
#1 - Mewtwo
The best Pokemon there is with a CP that can go over 4,000. Mewtwo has devastating legacy attacks like Psystrike. What makes it the best Pokemon is that even in neutral matchups, trainers have the advantage with Mewtwo.
Even without the legacy moves, Psychic and Focus Blast can obliterate most Pokemon.
#2 - Metagross
Metagross is one of the best Steel type Pokemon in Pokemon GO. Its legacy move Meteor Mash is arguably one of the best steel type moves in the game. Metagross is a very bulky Pokemon. This is one of the reasons why this Pokemon can be found guarding gyms in Pokemon GO.
#3 - Slaking
Slaking is another bulky Pokemon usually seen guarding gyms in the game. It has Earthquake, which is strong against Fire, Steel, Rock, Poison, and Eectric types.
#4 - Groudon
This legendary ground type Pokémon in Pokemon GO can withstand a lot of damage and has Dragon Tail and Earthquake as a part of its move sets. Solar Beam also happens to be a part of its moveset in Pokemon GO.
It is resistant to Rock, Poison, and Electric type Pokémon but is vulnerable to Grass, Ice, and Water type.
#5 - Zekrom
A legendary Electric/Dragon type Pokemon, Zekrom first appeared in the Unova region. This Pokemon is resistant to Steel, Water, Grass, Flying, Fire, and Electric type Pokemon.
Effective counters are Ice, Dragon, Fairy, and Ground type Pokemon. Charge Beam and Wild Charge deal the highest attacking DPS, while the best defensive moveset is Outrage.