>>27335948>>27335971>>27335982It has one of the highest max CP ceilings in the game (~2900), surpassed only by Snorlax, Dragonite and the legends, so it generally always has a higher base CP level than 90% of other pokemon when freshly acquired
Since very few people spend a lot of time actually powering up their mons past their starting stats, Vaporeon will generally be stronger than not-Vaporeons. This can be circumvented if you happen to have powered up one Pokemon to its max level, but once again, very few people actually spend their stardust on that
Why is Vaporeon so OP? All of the CP levels in the game are completely arbitrary, so somebody on Niantic just probably really likes Vaporeon (and hates Jolteon, whose max Cup is like 2400)