As part of Pokemon Go's major update last week, Niantic readjusted the attack speed and strength of many of its moves. Most affected were quick moves, as their attack duration increased, meaning that players could dish out less damage per second. Yesterday afternoon, Niantic rebalanced move strength and speed for a second time, reducing the damage of many quick attacks, but decreasing their attack duration. The amount of energy a quick attack generates (which fills the charge attack meter) has also been adjusted on many attacks.
This isn't the first time Pokemon Go has adjusted its attack metrics, but this is the quickest that two rebalances have occurred so close together. The rebalances are important as they shift Pokemon Go's metagame, which is centered around attacking and defending gyms. Players were still adjusting to the last set of changes, but now they're trying to determine what Pokemon are the best attackers and defenders once again.
According to the Pokemon Go Info website, which calculates a Pokemon's effectiveness based on their base stats and move types, Alakazam is now the most powerful attacker in the game when armed with Confusion and Future Sight. Dragonite is the second most powerful attacker with Dragon Tail and Outrage, and Espeon is third when it knows Confusion and Future Sight.
WWG will cover any new Pokemon Go updates as they happen.