Chansey has recently buffed, following the changes that was made in the Combat Power (CP). Niantic thought of making changes into the CP formulas for the purpose of introducing variety into the game. Recently, Chansey was given a +157.08% CP increase, and is continuing on becoming a top gym contender.
According to the report from Otakukart, Chansey is now considered to have the most ideal combine stats in the Pokemon Go game. She has climbed the top spot due to the values of her combine stats of stamina, attack, and defense. Niantic said that CP-tinkering might become common soon enough, and this recent update of the game only allows Mewtwo to beat Chansey's stats.
However, Chansey still seems to have better combined stats as compared to the legendary birds as well as Mew. Another interesting fact is that Chansey's evolved form is called Blissey, and it is the only Pokemon that can make it to the top spot considering all of its combined stats and its current formula will not be modified.
On the other hand, users on Reddit are discussing about where Chansey could be found. One user said that Chansey might be spawning in hospitals, but there were no sight of it in any trackers. Meanwhile, Chansey will also receive an evolution when generation 2 update will arrive. That means it will be expected that the said Pokemon will be a competitor in Pokemon gyms in the future. Though the Generation 2 update release date is still unconfirmed, players are suggested to start saving up their candies in preparation for the major patch of the game.
For those who are still unfamiliar with the generation 2 evolution chart and which candy that is needed to be saved, check on the link here for the evolution guide, the max CP chart for each generation 2 Pokemon are also revealed online.