Pokemon Go players have discovered a bug that turns Mega Evolved Pokemon into major powerhouses beyond what the game intended. Last month, Pokemon Go introduced Mega Evolution as a new mechanic to the game as a way to temporarily power up certain Pokemon. While players complained about the cost and time needed to Mega Evolve a Pokemon, players have discovered an exploit that gives Mega Evolved Pokemon a CP of 12,000 or more. The exploit affects only Pokemon that were powered up by their trainer prior to their Mega Evolution. When that Pokemon is Mega Evolved, they functionally receive the boost they received from its previous Level Up a second time. The lower a Pokemon's level was originally, the more of a boost it receives when it Mega Evolves.
To provide a more concrete example - if a Level 1 Beedrill is powered up to Level 40 and then Mega Evolved, the Pokemon would have a CP as high as 12294 instead of its intended CP of 3556. PokeBattler confirmed that this bug seems to impact any Pokemon that was powered up prior to Mega Evolution, even though not all Pokemon show the same heightened CP as Mega Beedrill.
It was also discovered that Mega Evolved Pokemon do not buff themselves while in battle, which is contrary to what Niantic has communicated in past blog posts about Mega Evolution. Only other party members receive this additional boost.
If players can get their hands on enough Mega Candy, it seems like now is a good time to Mega Evolve their Pokemon. Having a Pokemon with a massive unintended buff seems like an easy way to run through battles or raids, and it's unclear how long it will take for Niantic to fix what seems to be an obvious error with the game. We'll provide more information about the bug as it's discovered.