Chansey >> Blissey
Blissey is the second (and final) stage evolution of Chansey, and let me tell you, she is one hell of a tank. Seriously, this girl can take a beating. The route to obtaining a Blissey in the original games was to increase your Chansey’s happiness to a certain point, level it up, and it would evolve.
In Pokémon GO, however, it’s just 50 Chansey candy that are required.
Tyrogue >> Hitmontop
This is where things might start to get confusing for players who aren’t familiar with Gen 2. Hitmontop is the second (and final) stage evolution of a Pokémon named Tyrogue, and while Tyrogue isn’t actually a Gen 1 Pokémon, Hitmontop is on this list because Tyrogue’s other two evolutions are Gen 1 Pokémon: Hitmonlee and Hitmonchan.
I believe that when Tyrogue (and Hitmontop) are added to the game, Hitmonlee and Hitmonchan candy will turn into “Tyrogue” candy, and will be used to evolve Tyrogue into Hitmontop.
Therefore, hoarding Hitmonchan and Hitmonlee candies will allow you to evolve a Tyrogue into a Hitmontop as soon as you encounter a few in Gen 2. Makes sense? Definitely.
[Update] – As it turns out, it does indeed require 50 Tyrogue candy to evolve into Hitmonlee \ Hitmonchan \ Hitmontop.
Porygon >> Porygon2
Porygon2 is the second stage evolution of Porygon, and is one weird looking Pokemon. To evolve your Porygon in the original games, you needed to trade one that was holding an item called “Up-Grade”.
Since Porygon2 is Porygon’s one and only evolution in Gen 2, it takes 50 candy and a Up-Grade (special item) to evolve in Pokemon GO.
Slowpoke >> Slowbro / Slowking
Slowking is Slowpoke’s alternative evolution, much like Eevee. Since Slowpoke requires 50 candy to evolve into Slowbro, evolving Slowpoke into Slowking costs 50 Slowpoke candy as well with the addition of a King’s Rock (special item).
Slowbro is a decent tankish Pokemon, so having a Slowking around to defend Gyms would probably be a good idea when Gen 2 rolls out.
Which Gen 2 evolution are you looking forward to the most? Let us know in the comments!